FEEDING EXPERIMENTS WITH ISOLATED
FOOD-SUBSTANCES.
BY
THOMAS B OSBORNE and LAFAYETTE B MENDEL,
With the Co-operation of EDNA L. FERRY.
(From the Laboratories of the Connecticut Agricultural Experiment Station and
the Sheffield Laboratory of Physiological Chemistry of Yale Uniyersity )
WASHINGTON, D C
Published by the Carnegie Institution of Washington
carnegie xisrs'i'iTxmoisr of Washington
Publication INo 156, Fart XI
PRESS OE GIBSON BROS
■WASHINGTON, D C.
TABLE OF CONTENTS
p \ge
Introduction 55
Influence of various conditions on nutrition of white rats 55
Effect of long caging 55
Monotony of diet 56
Palatability of food 56
Physical texture of the food 56
Digestibility of the food 56
Need of "roughage** 57
Inorganic constituents of the food 57
Effect of extraneous and accidental factors
Earlier experiences of the authors 59
Prolonged maintenance on isolated food substances 59
Relation of nitrogen balance to weight of rat 60
Changes in the method of caging and feeding 60
Alimentary bacteria and nutrition 61
Addition of faeces to the diet 61
Nutrition and growth 03
Normal rate of growth of male and female white rat 63
Normal growth as influenced by nutrition 64
Relation of energy supply to growth 6s
Maintenance versus growth 65
Relation of protein to growth 60
Growth with insufficient food supply 66
Experiments of Waters on cattle 67
Experiments of Aron on dogs 6S
Measurements of poorly nourished children 70
Suspension of growth on a maintenance diet 7 1
Detailed measurement of stunted rats 72
Underfeeding contrasted with a maintenance diet 74
Effect of stunting on the growth impulse 75
Realimentation of stunted rats 77
Disproportionate growth 7 7
Effect of partial starvation on body-weight 77
Effect of partial starvation on nervous system 7S
Comparison of milk and mixed diet 79
Preparation of "protein-free ** milk 79
Experiments w’-ith isolated proteins and “protem-free milk** 82
Critique of the non-protein factors in the diet 82
Adequate and inadequate proteins S3
Discussion of the results and their bearings 84
'The charts and their explanations 86
Index of charts with reference to food-mixtures and proteins fed 86
xxx
FEEDING EXPERIMENTS WITH ISOLATED FOOD-
SUBSTANCES.
PART II.
INTRODUCTION.
In Publication 156 of the Carnegie Institution of Washington
we have discussed some of the problems of nutrition which have
been raised by the newer investigations in the field of protein chem¬
istry. The literature bearing on the feeding of isolated proteins was
there reviewed m some detail, together with critical considerations of
previously available experimental data We described a plan for
the study of metabolism and illustrated a method of investigation
in which white rats were the experimental animals For the details
involved, our earlier paper must be consulted A few protocols were
there presented to show that the outlined mode of investigation
offered a promising means for attaching certain questions m the
field of nutrition
INFlvUFNC^ OF VARIOUS CONDITIONS ON NUTRITION OF WHITE RATS
Numerous contingencies may arise to modify or vitiate the re¬
sults of experiments in which animals are kept in cages and fed upon
artificially prepared mixtures of isolated food-stuffs, quite independ¬
ent of the factors inherent in the food-stuffs themselves or the com¬
binations in which they are exhibited. Among these possibilities, the
caging itself, involving continued restraint and limited opportunity
for exercise, suggests an unfavorable environment This factor can
at length be disposed of
Donaldson has concluded, from the best data obtainable, that
“the three-year-old white rat is very old, and is justly comparable
to a man of 90 years 99 f Rats have been kept in our cages in appar¬
ent good health and without difficulty during periods of more than 14
months-a very considerable part of the span of life in these animals
(cf. Charts XXIII, XXIX, XXX).
^Feeding experiments with, isolated, food-sub stances, by Thomas B Osborne and
Uafayette 33 Mendel, with the co-operation of Edna D- Ferry. 1911. Pp 53
fU. H Donaldson A comparison of the white rat with man m respect to the growth
of the entire body. Boas Memorial Volume, New York, 1906, p 6.
55
56
feeding experiments with isolated food-substances
Monotony of diet has been urged as an obstacle to success where
the same food mixtures are daily furnished'without change over long
periods of time Very closely associated with this is the question of
the palatabthty of the diet The two factors need, however, to be
distinguished The palatability of the diet has, perhaps, been over¬
emphasized in recent years in its bearing on the real nutritive value
of foods It applies primarily to the individual with highly organized
nervous system and psychical functions The quality found m foods
which are unpalatable because they disgust or nauseate is something
positive, the negative property of lack of palatability, t e , absence
of stimulating taste, etc , is not necessarily a serious obstacle In any
event the palatability of the diet is difficult to determine or regulate
and in attempting ,to control it experimentally in animals physi¬
ologists have been guided very largely by anthropomorphistic con¬
siderations
We have now gathered observations which lead us to dismiss the
idea that monotony per se leads to anorexia or other forms of nutri¬
tive failure in our animals, despite the comment which this feature
has received from other investigators. There is no convincing reason
why a continued unvaried diet should necessarily be unphysiological,
one need only recall the fact that the diet of all sucklings is the same
from day to day, and that many of the domestic animals are satis¬
factorily maintained on rations which are scarcely altered in quali¬
tative make-up except at long intervals We have observed rats in
the same cage for considerably more than a year, during which the
daily diet was invariably furnished in the form of our food-pastes
In some of these the composition of the paste was practically the same
during these very long periods (cf Charts XXVII, XXVIII, XXIX,
XXX) It is true that we could point to many failures to maintain
rats on an unchanged diet continued over much shorter periods. One
must not, however, here confuse monotony with the real cause of
decline In these latter cases some deficiency or defect in the monot¬
onous feeding sooner or later brings on a physiological state where
anorexia occurs, and the advantage which a change of^diet initiates
ought primarily to be ascribed to the alteration in the food ingredi¬
ents rather than the relief from the sameness of the intake
Among factors referring more directly to the nature of the food
itself, the physical texture and digestibihty of the nutrients must be
taken into consideration. The structure of the food materials may,
under ordinary conditions of diet, influence its utilization in no small
degree; and the low “coefficients of digestibility” shown by many
foods of plant origin testify to this fact In our experiments the
products fed were isolated and reduced to a state of very fine com¬
minution. At most, therefore, some inherent indigestibility of the
individual foodstuffs employed might be concerned. Experiments
INTRODUCTION.
57
by M S. Fine,* while they do not completely do away with, this
possibility, make it more evident than before that incomplete diges¬
tion is, in the case of plant products, for the most part associated
with the peculiar vegetable tissues therein contained, rather than a
specific resistance of the isolated nutrients.
The need of “ roughage ” to facilitate the normal evacuation of
the gut has also been debated. We have, as a general procedure,
added the indigestible polysaccharide carbohydrate agar-agar to food-
pastes in order to approximate more nearly the conditions which
prevail where cellulose enters into the mixed dietary It can not be
maintained, however, that this is necessary for satisfactory nutrition,
for we have maintained animals over a year on foods (cf. Chart
XXIX) devoid of indigestible principles, if perhaps an exception be
made of some of the inorganic ingredients It is well known that
inorganic salts, notably bone ash, may exert the same influence as
cellulose in giving bulk to the faeces; and they are often so employed
in the technique of metabolism experiments at the present time f
Aside from the proteins, in which our experimental interest has
been primarily centered, our attention has been drawn more and
more to those components of the diet which are not sources of energy,
yet fundamentally indispensable—namely, the -inorganic compounds
It is possible that further investigation will compel the inclusion of
some of the more vaguely defined and unknown members of the
groups spoken of as extractives, lipoids, etc , in this category Every
attempt made by us to approach the solution of the problem of
inorganic salts in the dietary has brought fresh surprises.
When ForsterJ fed dogs and pigeons on salt-free foods he made
the interesting observation that the animals speedily died—more
rapidly even than when all food was withheld He concluded *
Der im Uebngen in Stickstoffgleichgewicht sich befindende thiensche
Organismus bedarf zu seiner Erhaltung der Zufiihr gewissen Salze, sinkt
die Zufuhr unter einer gewisse Grenze oder wird sie ganzlich aufgehoben,
so gibt der Korper Salze ab und geht daran zu Grunde.
The classic experiments of Eunin§ on mice led to a somewhat
different interpretation of the need of salts. He showed that the
animals survived longer on a diet containing an addition of sodium
carbonate to the ash-free food than when sodium chloride was added.
In the latter case the duration of life corresponded approximately
with that observed on a salt-free dietary. From these facts it was
argued that the foremost value of the sodium lies in its capacity to
neutralize the acids (sulphuric, phosphoric) formed in the metabolism
*M. S. Fine Dissertation, Vale University, igu (unpublished). Cf Mendel and
Fine Journal of Biological Chemistry, 1911, vols. x and xi.
fCf. Uothrop* American Journal of Physiology, 1909, xxrv, p 297.
jForster- Zeitschnft ffir Biologie, 1873, ix, pp. 297-380
§T, untn _ Zeitschrift fur physiologische Chemie, i88r, v, p. 31.
58 SEEDING EXPERIMENTS WITH ISOLATED EOOD-SUBSTANCES.
of proteins Sodium chloride obviously has no potential neutraliz¬
ing power. If the usefulness of the salts were associated solely with
their specific character as salts, the salts of sodium ought to be some¬
what comparably efficient
Th e. function of the inorganic salts is by no means exhausted, how¬
ever, by the simple action of chemical equilibrium It would lead us
too far afield in this place to discuss the problem in detail Charts
XI, XII, and XIII, Part I, pp 38-39) showing the marked differences
induced by alterations in the inorganic salts of the diet, the other
food components remaining unchanged, are highly suggestive We
have since then made numerous attempts to improve upon the salt
mixture empirically selected and prepared somewhat in imitation of
the ash of milk. Rats were kept alive (while they steadily declined)
84 days on a food mixture which analysis showed to contain only
minimal, inevitable traces of ash (016 per cent, a considerable part of
which was phosphoric acid derived from the casein). Chlorides were
entirely lacking, distilled water being furnished for drinking In
view of this it is necessary to proceed with extreme caution in draw¬
ing conclusions from observations extending over brief periods We
shall refer to the subject again, it being sufficient here to emphasize
the subtle and specific value of the salts The lack of knowledge in
this field has furnished an obstacle which we have only lately suc¬
ceeded in overcoming in part
Even when all these varied conditions are taken into account,
there still remain, as we have pointed out before, extraneous inci¬
dents and accidental factors apart from nutrition itself, which may
complicate or vitiate experiments like those projected. Disease, old
age, injury, may be mentioned m illustration Failures to maintain
nutrition successfully under such extreme conditions do not neces¬
sarily imply a deficiency or inadequacy of the dietary Accordingly,
successful experiments must be given far greater weight than failures,
where so many possibilities of detrimental influences, aside from the
diet itself, are hable to arise over prolonged periods of observation
Some of the uncertainties have been eliminated by the experience
previously gained For example, the intercurrent diseases of our
animals have been almost entirely excluded by the use of rats raised
in the laboratory for this research By the prompt elimination of
diseased animals, by scrupulous attention to the conditions of the
cages and feeding arrangements—in other words, by painstaking
attention to hygienic factors—we have succeeded in maintaining a
large number of animals in exceptionally good health, so that they
have become the more suitable to permit of accurate conclusions
regarding the effects of the diets studied Furthermore, the age and
hereditaryfactors in our animals are now known to us, so that another
source of uncertainty has disappeared.
EARLIER experiences oe the authors
59
EARLIER EXPERIENCES OE THE AUTHORS.
As the result of the first year’s experiments, it was found possible
to maintain rats m health and apparent nutritive equilibrium over
considerable periods of time on a mixture of isolated food-substances
containing isolated proteins as the source of nitrogenous intake For
example, one protocol (Chart XXX) shows that a full-grown rat*
was maintained satisfactorily in this way for more than 217 days on
glutenin, the animal continuing on this r 4 gime at the time when the
earlier report was prepared for publication Rats were likewise main¬
tained on diets in which other proteins, notably casein alone or in
combination with isolated vegetable proteins, formed the sole nitrog¬
enous food component, over periods of time exceeding any previously
reported, at least under conditions in which the “purity” of the
dietary substances was carefully maintained unchanged over equally
long periods of time By maintenance we do not merely mean that
the animals remain alive No feeding experiment is to be regarded as
successful in fulfilling the nutritive requirements unless the ammals
approximately maintain their weight and health (or make normal
growth if they are at a stage where this is still to be expected)
Although these apparently successful experiments indicated that
the combinations of isolated food-stuffs employed satisfied the nutri¬
tive requirements of the rats and consequently constituted a com¬
plete food for the maintenance of mature animals, a prolongation of
the observations has led to a less favorable outcome A continuation
of the experiments over longer periods has shown that in every case,
sooner or later, the animal declined, and unless a change in the diet
was now instituted within a comparatively short time the animals
died The Charts XIV, XV, XVI m our earlier paper illustrate this
very well The rats 23, 24, 25 were maintained without noteworthy
alterations in weight over 130 to 160 days on a constant mixture
including a single protein The animals ate well, as the food records
show, until the final period of decline
These records can be duplicated, especially in respect to the de¬
cline, by many others, as for example Charts XL-I, XUI, LXXVIII,
I/XXIX, I/XXX, CII, CXV, CXVI appended to this report The
history of rat 71 is particularly instructive on this point, f This
animal (see Chart XXX), weighing 257 grams on April 5, 1910,
was put upon a diet containing casein (12 per cent) and glutenin
(6 per cent) as the only proteins Subsequently glutenin alone
(164 per cent after 69 days and 18 per cent after 104 days) formed
the protein of the diet The rat continued in excellent nutritive
*The earlier data regarding this animal, rat 71, are given in Publication No. 156,
Carnegie Institution of Washington, p 47 ff.
fThe earlier data -mil be found in Publication No 136, Carnegie Institution of Wash¬
ington, pp 47-48.
60 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
condition, eating well and exhibiting favorable nitrogen balances,
until the end of 9^ months, when a gradual decline was observed
When the animal, at the end of a total feeding period of 335 days
(42 days after the onset of the decline) was reduced to 162 5 grams
in weight and near death, an attempt was made to see whether
the decline was due solely to improper food or to the onset of old
age or disease With mixed food realimentation took place at once
and the rat regained its weight in a week A resumption of the
former glutenin food during 35 days gradually led to a second decline,
which was promptly checked by a change in the diet involving only
the non-protein components of the food mixture Here, then, is a
record of the feeding of a full-grown rat, with the exception of 7 days,
during a period of 454 days on a diet of isolated food-stuffs and on a
diet containing a single protein, glutenin, for 371 days This obser¬
vation is remarkable because of the exceptional duration of the
experiment It is apparent, therefore, that as a maintenance diet our
food lacked something other than protein and energy
It remains to be shown precisely what the lacking component
of our earlier diets is, whether some organic constituent or a peculiar
proportion of inorganic ingredients In any event it is evident that
our original artificial food mixtures are incapable of supporting life
indefinitely. Aside from this, however, records like that of rat 71
living on glutenin as the sole source of protein (see Chart XXX), or
rat 133 (Chart TXX) on edestin, in contrast with rats XI, xiv, 146,
and 157 (Charts CXXVI, CXXVII, CXXVIII, and CXXIX) on
zein indicate the possibility of nutritive inequalities among the
proteins themselves Marked deficiencies tend to manifest them¬
selves in comparatively short periods of time In all of these cases
the food actually consumed supplied sufficient energy for the imme¬
diate needs of the rats under investigation.
In the continuation of our experiments we have tried to profit
by the first year’s experiences The methods ha ve not been materially
altered, except that the determination of the nitrogen balance has
been omitted for the present. We learned from very numerous trials
that it runs parallel with gain or loss of weight, and that the food
intake varies closely with the weight of the animal, thereby making a
record of the nitrogen unnecessary for judging the nutritive status of
the rats employed. The same cages as heretofore have continued to
prove very satisfactory. Instead of being rested on glass funnels for
the collection of urine, they are now placed over a frequently changed
sheet of absorbent paper (paper napkin) upon an enameled tray or
pan. The fluid excreta thus promptly absorbed are frequently
removed. It has already been pointed out that the food mixtures,
prepared in paste form to prevent scattering by the animals and
make it possible to obtain accurate records of the quantities eaten,
ALIMENTARY BACTERIA AND NUTRITION 61
are not ideal in composition The inclusion of 20 to 45 per cent of
fat in the diet—a condition necessitated by the requirements of the
experiments as outlined—seems like an excessive amount, neverther
less the utilization appears to be satisfactory and attempts to devise
less objectionable modes of feeding have been unsuccessful in our
hands.
ALIMENTARY BACTERIA AND NUTRITION
In the course of our later studies we have been forced to take
cognizance of the possible rdle of the bacterial flora of the alimentary
tract in relation to appropriate nutrition The water-free, fat-nch
food characteristic of our experimental dietaries is not, broadly
speaking, a particularly favorable medium for the development of cer¬
tain groups of bacteria. The food of our animals therefore probably
introduces into the digestive tube of the experimental animals bac¬
terial invaders somewhat different from those which normally inhabit
the alimentary tract of rats living on a free mixed diet It is quite
conceivable, therefore, that the bacterial conditions may be altered
markedly as a result of the restriction m the growth of certain groups
or the facilitation of the development of still others in the alimentary
tract under these changed and sustained conditions of altered diet *
It is well known, for example, that m higher animals the preponder¬
ance of acid-producing organisms—to use a single illustration—may
lead to an inhibition of the growth of the putrefactive group
Guided by such considerations and the observation that those
rats that have been maintained for long periods on diets with isolated
food-stuffs become koprophagists, we have initiated the plan of feed¬
ing small quantities of the fseces of rats living on ordinary mixed food
to some of our experimental animals, particularly in cases where
symptoms of nutritive decline had become manifest In nearly every
instance the occasional addition of a small amount of the faeces from a
normally fed rat at once stopped the decline 111 weight of the experi¬
mental animals to which a single protein was being fed. The results
in almost all of these cases have been sufficiently striking to warrant
a further pursuit of this topic In our experiments there appears to
be an unmistakable favorable influence induced by the occasional
addition to the dietary of normal “seces with their high bacterial
content. It must not be overlooked that other components besides
bacteria, notably inorganic salts and unknown compounds, are also
furnished by this means, but the quantities involved have always
been very small. Further investigation will be necessary and is
already projected
The procedure in the case of these faeces-feeding trials consisted
in introducing small amounts (about o 5 gm ) of air-dry excrement
*Cf Herter and Kendall Journal of Biological Chemistry, 1910, vn,p 203; Kendall
Journal of the American Medical Association, April 15, 1911.
62
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
of rats on mixed food into the cages twice a week. It is an interesting
observation that when the rats kept on a mixture of isolated food-
substances were offered a choice between their own faeces and those
of rats on mixed diets, they invariably chose the faeces of the latter
In many cases we have noticed a marked improvement in the nutri¬
tive conditions of animals maintained on a single-protein dietary
when other rats were introduced into their cages for breeding pur¬
poses. In view of the favorable influence exerted by feeding the
faeces of rats living on mixed food, it is quite likely that the presence of
the strangers in the cages furnished a suitable opportunity to obtain
“normal” faeces This may explain the favorable results noted, in
contrast with the negative effects seen where several rats living on
the same single-protein diet have been maintained in the same cage
The extent of the influence exerted by what we have, in the
absence of a better explanation, assumed to be bacterial influences, is
illustrated in some of the appended charts, the periods at which the
faeces feeding was begun being indicated The favorable effects have
not been confined to experiments with one protein, but are mani¬
fested with casein (see Charts XXXIX, XL, XLI, and XLII), with
edestin (see Charts LXVI, LXVII, LXVIII, and LXIX), and with
gliadin (see Charts Cl, CII, and CIII) Two failures may likewise be
recorded, viz, an ultimate one with casein (Chart XLI) and a com¬
plete one with edestin (Chart LXXVII) as the protein component
These were not due to incapacity of the animals to grow, since fur¬
ther alteration of diet brought marked improvement
The influence of faeces feeding is especially striking in the case of
the gliadm tests, since without the addition of the faeces it has been
almost impossible to attain satisfactory nutritive condition with this
protein plus the special non-protein components of the food here
employed. It is instructive therefore to compare such failures (cf.
Period 2, Charts CXV and CXVI) with Charts Cl and CIII, in which
faeces feeding was resorted to
In four of the experiments with edestin-food alluded to and re¬
corded on Charts LXVI, LXVII, LXVIII, and LXIX, fresh faeces
were not actually introduced into the cages, but the improv emen t,
and even growth, in these young rats is coincident with the oppor¬
tunity afforded to obtain “normal” faeces when other rats were daily
introduced into the cages for a few hours.
In Chart CII is seen the result of an attempt to determine
whether the favorable influence of the faeces is actually of bacterial
nature. Faeces were fed as in the comparable gliadin experiments
(Charts Cl and CIII); but they were previously sterilized by thrice
repeated heating in an atmosphere of steam. The decline of the
animal was not prevented to the same extent with sterilized as with
normal faeces. Further trials are necessary in this direction, and our
NUTRITION AND GROWTH.
^3
experience, though limited, invites attention anew to the possible
nutritive functions of bacteria m the alimentary tract. Some of the
aspects of this problem are referred to in our earlier paper *
NUTRITION AND GROWTH
The criteria of adequate nutrition are quite different in the case
of growing animals from those applying to adults of the same species
During the period of adolescence it is not sufficient to maintain a
condition of nutritive equilibrium and constancy of form or body-
weight In this stage of an animal’s existence there should be evi¬
dences of development, and growth should manifest itself in a change
of size The curve of growth, expressed in changes of body-weight, is
remarkably constant and characteristic for each species under the
ordinary conditions of nutrition and environment The individual
values may at times fluctuate about a mean, but in the majority of
cases the excursions from the average are not extensive
In Chart XXII are reproduced curves illustrating the average
normal rate of growth of the white rat, both male and female The
statistics for two of the curves are taken from Donaldson,! whose
observations we have repeatedly verified m their general features
A third curve on the same chart represents the results of our own
observations on the growth of the female white rat, regardmg which
data are less abundant. It will be noted that the curves of growth
for the two sexes do not completely coincide in type After an age
of 70 days, represented by a body-weight of about 100 grams, the rate
of growth is somewhat slower in the female than m the male In¬
deed, the females rarely attain the large weight and size exhibited by
the normal adult males of the same age, even m the case of animals
from the same litter We gain the impression that our “breed” of
rats may in general be somewhat smaller than those measured by
Donaldson and his collaborators At any rate, the data available
for statistical purposes are not very extensive and the curves here
presented must have only a provisional value until more numerous
measurements are made. In connection with certain of our experi¬
ments it may be stated that “the effect of mating on the growth-
curve for the males can probably be neglected ”% In the case of
females, the effect of the bearing of young is, according to Watson, §
“to render the mated rats slightly heavier than the unmated—some
of the excessive weight being due to the larger amount of fat present
in the mated animals ” Two charts (XXIV, XXV) are appended
*Camegie Institution of Washington, Publication No. 156, p 3
fDonaldson A comparison of the white rat with man in respect to the growth of the
entire body Boas Memorial Volume, New York, 1906.
JCf. Donaldson ibid, p 8
§ Watson Journal of Comparative Neurology, 1905, xv, p 523.
64 feeding Experiments with isolated Food-substances
to illustrate the influence of the course of pregnancy on the growth-
curve of female rats of different sizes
Making allowance for these minor divergencies, the striking
uniformity in the progress of development in an animal nevertheless
is a specific racial characteristic, and gives to the curve of growth a
unique value as an index of the conditions which determine it.
Growth is affected by two factors nutrition, and what Rubner has
termed “Wachstumstrieb ” or growth-impulse. The latter factor is
inherent in the animal. The limits are determined by heredity and
can not be altered materially by the most abundant diet ‘ ‘ Eine noch
so reichliche Ernahrung vermag die in derRasse und deren Vererbung
gelegenen Grossen- und Massenbegrenzungen nicht zu mehren ”*
We are not prepared, at this time, to discuss the nature of the
hereditary factor or impelling “force ” in growth f Aron writes
Die Natur des Wachstumstnebes ist dunkel Sie ist erne Funktion der
Zellen, 1 m besonderen der jugendlichen Zellen Welche Faktoren diesen
Zelltneb regulieren, wissen wir nicht, vor allem nicht, warura er allmahlich
aufhort. Ob hier die Zeitdauer seiner Wirksamkeit, ob die erreichte Grosse
des Individuums den Ausschlag fur das Abklmgen des Wachstumstnebes
gibt, ist bis jetzt nicht entschieden J
Rubner has attempted to formulate its character
Die eine grosse Unbekannte auf dem Gebiete der Wachstumsphysiologie
ist der Wachstumstrteb, der m gesetzmassiger Weise den Gang der Entwick-
lung, Massenzunahme, durch die Regelung der Ernahrung leitet Den
Urgrundha.t6xe.sex Wachstumstrieb in der Geschwindigkeit derKemteilung,
wie wir noch sehen werden leitet sich hieraus der ganze Prozess des Stoff-
umsatzes ab Die Kernteilungsgeschwmdigkeit ist offenbar etwas der
Spezies Eigentumliches, somit sind wir nicht in der Lage, vorlaufig tiefer in
dieses Problem vorzudrmgen §
The second factor ingrowth, namely, nutrtHon , can be approached
more easily by the experimental method It is along this line that
we have hoped, therefore, to be able to attack some of the problems
of the relative value of the individual foodstuffs It is well known
that growth can be retarded by means involving the nutrition of
the individual. Waters has well summarized the situation in these
words:
The upper limit of the size of an animal is determined by heredity The
stature to which an animal may actually attain, within this definitely fixed
limit, is directly related to the way in which it is nourished during its grow¬
ing period. Some of our approved theories have been so extreme as to hold,
in effect, that the animal must grow at its maximum rate practically every
•“Rubner Archiv fur Hygiene, 1908, rxvr, p 82.
fCertain aspects are considered in C S Minot The problem of age, growth, and
death. New York, 1908
JAron* Biochemische Zeitschrift, 1910, xxxp. 207
§Rubner Archiv fur Hygiene, 1908, nxvi, p., 86.
Nutrition and growth
65
day from birth to complete maturity in order to reach its normal size, or
the full stature fixed by heredity. In other words, it is assumed that the
animal has but one way of reaching its full stature and full development,
viz , by developing to its upper limit through its entire growth period This
assumes that the organism is utterly incapable of compensating for any
retarded development at any time m its growth period, either by a subse¬
quently increased rate of growth, or by extending, even in the slightest
degree, the growth cycle, much less by growing for a time at least when so
sparsely fed that no gam m weight occurs *
Rubner has expressed the r 61 e of nutrition in growth as follows.
Kanndie Ernahrung auch kemen Wachstumstneb schaffen, so kann sie,
wenn ungunstig und unzweekmassig, doch zu emem Hemmms des natur-
lichen Wachstums werden Wachstumsbehinderung 1st mnerhalb gewisser
Grenzen noch kerne Ursache einer Existenzgefahrdung, ein Kind, dem die
Nahrung normales Wachstum hmdert, stirbt deswegen durchaus mcht, es
holt spater leicht wieder em, was es versaumt hat Nur das steht
sicher, dass die Behmderung des Wachstumstnebes, wie dies wirklich
vorkommt, nicht wahrend der ganzen Wachstumspenode andauern darf,
da sonst allerdmgs die Grosse des Individuums dauemd Schaden leidet
Verlorene Korpergrosse in der Jugendzeit kann nach Vollendung der
Wachstumspenode mmmermehr abgeglichen werden Eme optimale
Ernahrung, wie die Wachstinnsci naht ung sem muss, stellt an die nchtige
Auswahl der Stoffe ganz andere Anforderungen als eme einfache
Erhaltungsdiat f
Obviously the energy problem plays an important part in the
nutrition of growing animals For the present we are primarily
concerned with the qualitative aspects of the diet rather than the
quantitative features of the food-intake These two factors may at
times stand in intimate relation to each other, improperly consti¬
tuted food may, for example, modify the amount eaten and therefore
the energy available for growth As was intimated in our first
report we have been able to arrest development in rats by feeding
mixtures containing a single protein, but inasmuch as the food
intake was not measured at that time, it was impossible to say
whether the chemical character of the diet or a quantitatively inade¬
quate food consumption was responsible for the dwarfing The fact
brought out was that in these young animals there could be a main¬
tenance of weight , precisely as in older rats
Waters has appropriately emphasized the necessity of a more
exact definition of what is meant by maintenance, in contrast with
growth. He writes
It has long been assumed that the body of an animal, when supplied
with only sufficient nutriment to maintain its weight, remains constant in
composition and that no growth or production or change of any sort occurs.
*H J Waters The capacity of animals to grow under adverse conditions Proceed¬
ings Society for the Promotion of Agricultural Science, 1908, xxix, p. 3.
f Rubner Archiv fur Hygiene, 1908, i,xvi, pp 82-83.
66
feeding EXPERIMENTS with isolated Pood-substances
It is true that the term maintenance has been used somewhat loosely, but
in general we have been in the habit of regarding the animal in maintenance
when its live weight was constant A more correct definition of the term
would perhaps be to say that the animal was in maintenance when its body
was m energy balance, but the live weight has been the conventional
measure of our maintenance values.*
It is generally admitted that the proteins satisfy several functions
in a growing organism as well as in the adult The first is that of
maintenance, corresponding with what has been termed the “ Abnut-
zungsquote, ” or wear-and-tear, by Rubner This makes good the
inevitable losses occasioned by the processes of metabolism, cellular
and secretory processes, etc It is a small yet ever present need
for protein (as well as energy), representing m a general way the
minimal protein need of the stationary organism Any excess of
protein beyond this maintenance requirement may, m the adult,
experience temporary storage (“ Ansatz”) or be devoted to dynamo-
genic purposes, but in the organism capable of development it con¬
tributes a share toward growth It should be emphasized that the
rate of growth is not by any means proportional to the excess of
protein available It is surprising, indeed, how small a content of
protein in the dietary suffices to make growth possible Rubner and
Heubnerf found, for example, that in suckling infants a protein
intake equivalent to 5 per cent of the total calories satisfies the protein
needs of maintenance, while 7 per cent permits of growth Rubner
writes
Das Wachstum 1st erne Funktion der Zelle, es kann durch unzureieh-
ender Eiweisszufuhr latent werden, aber Eiweiss vermag nicht die Wach-
stumsschnelligkeit uber die von der Natur gestreckten Grenzen zu heben,
daher wird mit steigender Eiweissmenge m der Kost prozentisch wemger
verwertet und das uberflussig zugefuhrte Eiweiss wird emfach als Brennstoff
verbraucht der isodyname Mengen N-freier Stoffe emspart Diese starke
Anziehung von Eiweiss zum Wachstum nimmt im I/aufe der Entwicklung
ab und 1st am grossten in der ersten Zeit des Eebens $
"Waters has found in his extensive studies on cattle that growth,
in the sense of changes of size and form, may occur even under
adverse nutritive conditions Fundamentally such investigations
touch upon the much controverted question as to the relative impor¬
tance of breeding and feeding in determining the shape and activities
of mature animals It is well known that by limiting the food supply
of an ungrown individual, its development may be retarded If the
underfeeding is prolonged through the cycle of growth, the full
stature limited by heredity may not be reached
*H J Waters The capacity of animals to grow under adverse condition Proceed¬
ings Society for the Promotion of Agricultural Science, 1908, xxxx, p 3.
tRubner and Heubner Zeitschnft fur experimentelle Pathologie, 1903,1, p. 1.
JRubner. Archiv far Hygiene, 1908, Lxvr, p. no
nutrition and growth.
67
Waters asked the question.
Will this animal of smaller stature be in the same proportion with re¬
spect to all the organs and the different parts of its body as though it had
been nourished to its full capacity and had attained its normal size and max¬
imum development ? Or will 111 this period of sparse nourishment a more
complete development occur in certain parts of the body than m other parts ?
In short, when there is not sufficient food supplied to the growing animal
to develop all of the organs and all parts of the body to their full limit and
extent, will the rate of development of certain of these organs or parts
diminish earher than others and will the development of certain parts cease
altogether before the development of other parts is diminished in rate and
is it possible that some parts may cease their development before that of
other parts
In actual experiments at the Missouri Agricultural Experiment
Station, Waters found that ungrown cattle may remain at a constant
body-weight for a long period of time, and yet increase in height and
apparently decrease their store of fat In other words, the skeleton
has grown, or at least the bones have lengthened Two interesting
illustrative protocolsf are reprinted’here, one, Table XXXI, m which
a stationary body-weight was maintained, the other. Table XXXII,
in which there was actual decline on a starvation ration
Table XXXI (from Waters, Table III —Shoy-ing Increase in Height at
Withers, Length of Head, Depth of Chest, Width of Chest, and Loss of Fat
in a Yearling Steer when Kept at a Stationary Bod\-W eight
No 595 Grade Hereford Born May 15, 1907 Nine and a half months old i*hen experiment began
Full fed four months pievious to beginning of trial Condition when put on maintenance medium
Weight at beginning of tnal r 609 2 lbs Weight at close of trial, 595 6 lbs Average of ten daily weights
Date
Height at
withers
Length
of head
Depth of
clicst
Width of
chest
- 1
1 Condition I
1908
cm
cm.
cm
cm
i
Feb
8
IOQ
38
56
35
Medium j
Mar
13
I 12 5
40
5s
36 5
Medium ’
Apr
I I
11 5 5
41
57 5
35 5
Medium to tlun ;
June
2
116
42
59
33 5
Common
July
1
117 5
44
58 5
34
Common
Aug
I
117 5
44
59
33
Common
Sept
2
i "7 5
1 44
59 5
33
1 Common to fair
Sept
2 Q
I IQ |
1 45 50
59 5
33 5
| Fair
Oct
30
r IQ 25 ]
! 45 75
59 5
31
j Fair
Nov
30
1909
HQ 5
1
45 75
1
59 5 ,
: 31
' Fair to thin
1
! Thm
Jan
1
ri 9 75 !
46 50
60 5
3 ° 75
Jan
30
1
riO 75
45 50
60 75
„ 30 75
| Thin
Total height m 12 months
! 10 75
7 50
4 75 '
*— 4 25
Per cent gain
| 9 36
19 73
8 48
*—12 1
Note —When slaughtered, carcass was'’classed as poor canner All visible subdermal and intramuscular
fat had disappeared
*—Denotes a loss
*H J. Waters The influence of nutrition upon the animal form Proceedings Society
for the Promotion of Agricultural Science, 1909, xxx, p 71.
fFrom H J Waters The capacity of animals to grow under adverse condition Pro¬
ceedings Society for the Promotion of Agricultural Science, 1908, xxix.
68
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
Table XXXI 1 (from Wvters, Table VI) — Sub-Maintenance
Steer No 591 Grade Hereford Born May 15, 1907 Experiment began Feb 26,1908
Age of animal at beginning of experiment, nine and a half months
Full fed four months before trial began and was m good condition
Weight at beginning of trial, 572 7 lbs Weight at close of trial. 490 4 lbs
Total loss m weight, 82 3 Ids Average daily loss o 43 lb —Denotes loss
Height at
Length of
Depth of
Width of
JJate
withers
head
chest
chest
1908
cm
cm
cm
cm.
Feb. 8
110 5
39
57
38 5
Mar. n
JJ 3
41 5
57 5
34 5
Mar. 28
115
42
35
Apr 11
114 5
41
58
33
May 2
116
42
57
33
June r
118 5
44
57 5
33
June 29
120
44
58
3 i 5
July 31
119
44 5
59 5
29 5
Aug 31
IIQ 5
44 5
58
29
Gam
9
5 5
1
- 9 5
Per cent
8 14
14 10
1 75
—24 6
The following is from Waters, in regard to a series of compara¬
ble cattle maintained by him on different nutritive planes, desig¬
nated as sub-maintenance, maintenance, and super-maintenance.
It is to be observed that there is no appreciable difference in the rate of
growth in height of these three animals on widely different nutritive planes,
from the beginning of the experiment (February) to the end of June. At
this time the curve of the sub-mamtenance animal flattens perceptibly A
month later, the maintenance animal is apparently responding to the in¬
fluence of the low nutritive plane As would be expected, m the case of
the super-maintenance animal, the rate of growth remains unchanged
It may be surprising to many [Waters writes elsewhere] that an animal
on maintenance, much less on sub-mamtenance, should show any increase
whatever in the width of hip or length of leg . Apparently the animal
organism is capable of drawing upon its reserve for the purposes of sustain¬
ing the growth process for a considerable time and to a considerable extent
Our experiments indicate that after the reserve is drawn upon to a con¬
siderable extent to support growth the process ceases, and there is no further
increase in height or in length of bone. From this point on the animal’s
chief business is to be to sustain life. This law applies to animals on a
stationary live weight as well as those being fed so that the live weight is
steadily declining, and indeed to those whose ration, while above main¬
tenance and causing a gam in live weight, is less than the normal growth
rate of the mdividual Such an animal will, while gaining in weight, be¬
come thinner, because it is drawing upon its reserve to supplement the
ration in its effort to grow at a normal rate.*
More recently Aronf has made comparable studies on growing
dogs. He formulated his problem in the following words*
“Was wird geschehen, wenn furkurzere oderlangereZeitinderNahrung
nur so viel Fnergie usw zugefuhrt wird, wie erforder lich ist, um den Frhalt-
*H J Waters How an animal grows Kansas State Board of Agriculture, Seven¬
teenth Biennial Report, 1909—1910,1, p 208.
fAron* Biochenusche Zeitschrift, 1910, xxx, p 207.
NUTRITION AND GROWTH
69
ungsbedarf des wachsenden Orgamsmus zu befnedigen, aber kein Ueber-
schuss, der als Wachstumsenergie dienen konnte ? Die nachstliegende
Annahme 1st, dass dann kem Wachstum stattfindet, dass der Wachstums-
prozess stillsteht Konnen wir nun wirkhch den Wachstumstrieb durch
Nahrungsbeschrankung unterdrucken ? Wie lange ? Und was geschieht
spater mit emem wachsenden Organismus, dessen Wachstum eine Zeixlang
hmtan gehalten worden ist? (p. 208 )
Aron succeeded by restricted feeding in attaining constancy of
body-weight in practically all of his dogs, in some cases during a
period of nearly a year The daily gains or losses fluctuated within
a few grams The description of the animals during the experiments
is of interest to us
Bei alien Hunden konnte man deutlich beobachten, wie die Tiere trotz
des Gewichtsstillstands wuchsen, d.h an Hohe und Lange zunahmen.
Dabei wurden die Tiere zusehends magerer, Fett und Muskeln schienen an
Masse abzunehmen, die runden Formen schwanden, die Knochen traten
eckig unter der Haut hervor, und schhesslich schienen die Tiere nur noch
aus Haut und Knochen zu bestehen Trotzdem waren die Hunde mcht
etwa schwach. Im Gegenteil, sie waren lebhaft, liefen und sprangen umher,
oft mehr als lhre normalen Brudertiere, die em zwei- oder dreimal zo grosses
Korpergewicht zu bewaltigen hatten Dieser Zustand zunehmender
Abmagerung unter standiger Grossen-, d h Langen- und Hohenzunahme
bei Konstantbleiben des Gewichtes dauerte je nach demGrade der Nahrungs-
entziehung [ungefahr 3 bis 5 Monate an Wurde jetzt, wenn das Tier
vollig abgemagert war, , die Nahrungsmenge wetter so genng belassen
wie vorher, so ging das Tier unter genngem Gewichtsverlust m volhger
Inanition zugrunde Wurde aber jetzt die Nahrungsmenge etwas erhoht,
wie bei Hund A, so hielt sich das Tier zwar vollkommen abgemagert, aber
auf konstantem Gewicht Und jetzt erweist sich dieser Geunchtsstillstand als
identisch mit W achstums still stand 1 Der Hund A 1st noch weitere 5 Monate
auf dem gleichen Gewicht gehalten worden, ohne dass sich nun m seinem
Aussehen nennenswerte Aenderungen konstatieren liessen
Durch geeignete Nahrungsbeschrankung gelingt es also, wachsende
Hunde beliebig lange auf konstantem Gewicht zu halten Naturlich darf
man mcht allzu junge Tiere nehmen Wahrend dieses Gewichtsstillstandes
gehen aber gewaltige Umwandlungen im Tierkorper vor, die sich ausserhch
m dem fortschreitenden Langen- und Hohenwachstum und der Abmagerung
dokumentieren
Offenbar ist trotz des Gewichtsstillstandes das Skelettweiter gewachsen
und hat mcht nur an Grosse, sondem auch an Masse zugenommen Folg-
lich mussen andere Korpergebilde (wie Haut, Fleisch, Organe usw)
an Gewicht verloren haben, denn sonst konnte ja das Gewicht des Tieres
mcht das gleiche geblieben sem Ebenso wie die Massenverhaltnisse der
einzelnen Korpergebilde haben sich nun hochstwahrscheinlich auch die
Mengenverhaltmsse der einzelnen Korperbestandteile, wie Fett, Eiweiss
usw , betrachtlich verschoben. (p 212.)
Aron’s analyses of the underfed dogs showing stationary weight
in comparison with well-fed control animals indicate that in addi¬
tion to the bones, the brain also was protected from loss of weight,
while the adipose and muscular tissue suffered notable losses. Most
striking is the degree to which water has replaced the tissue substance
70 REEDING EXPERIMENTS WITH ISOLATED POOD-SUBSTANCES.
utilized to compensate for the lack in the food, the blood especially
becoming distinctly “watery,” as the selected protocol shows *
Table XXXIII —Content, op Dry Matter in Various Tissues
Control dog
Underfed dog
Blood
"18 8
''s 1
Brain
1 24 6 I
19 3
Bones
! 57 2
40 0
Muscle
2Q 1
l 1
15 2
1
’"Protein=NX6K
It is apparent here, as in Waters’s experiments, that the energy
deficit has been furnished by the body. “Sind alle verfugbaren
Reservestoffe aufgebraucht, dann gewinnt der Krhaltungstneb die
Oberhand uber den Wachstumstneb, und das ‘Wachstum’ stockt ”
(Aron, p 222 )
In relation to our own later observations it is desirable to quote
Aron’s view regarding the impulse to growth He concludes
. . dass die innere treibende Kraft zum Wachsen uberhaupt in dem
Kemgerust des Korpers, dem Skelett, ruht Die Muskulatur verfugt
anscheinend uber gar keinen nchtigen Wachstumstneb Sie folgt dem
wachsenden Skelett nur dann, wenn die Ernahrungsveihaltmsse es erlauben,
vielleicht auf Grund rem mechamscher Krafte (Zug)
Recht interessant schemt zum Schluss noch die Frage, wie sich bei den
durch lange fortgesetzte Unterernahrung lm Wachstum zuruckgehaltenen
Tieren die Fntwicklung und die Entwicklungsfahigkeit verhalt Mem
Tiermatenal war mcht ausreichend, um em Studium der Geschlechtsorgane
der zwar 1m Alter der Geschlechtsreife stehenden, aber im Wachstum weit
zuruckgebliebenen Tiere zu gestatten Dagegen schemt mir die Beobach-
tung der Stimme auf em wirkliches Zuruckbleiben der Entwicklung auf dem
mfantilen Stadium zu deuten Die Unterschiede zwischen den Bruder-
tieren der ersten, zweiten und vierten Versuchsreihe waren auffallig Die
im Gewicht zuruckgebliebenen Tiere schnen kreischend wie junge Hunde,
wahrend lhre normalen Brudertiere mit tiefem Tonfall bellten In ganz
dem gleichen Sinne spncht die von Waters festgestellte Tatsache, dass seine
m Gewicht und Wachstum zuruckgebliebenen Tiere em Fleisch, das fur
‘Kalbfleisch’ charaktenstisch war, aufwiesen, wahrend sie dem Alter nach
schon “Rmdfleisch” besitzen sollten. (pp. 222—223 )
Studies of the relation of weight to the measurements of children
during the first yearf have also given evidence of “disproportionate ”
growth in the case of poorly nourished infants. Whereas there is, in
the normal infant, a fairly constant relationship between body-
weight and height, circumference of head, chest, etc., this is not true
where proper increase of body-weight is retarded by poor nutrition.
For example, in children whose weight at the end of the third month
•Arctr Biochetmscb.e Zeitschrift, 1910, xxx, p. 220
C. Fleischner Archives of Pediatrics, October 1906,
SUSPENSION OP GROWTH ON A MAINTENANCE DIET. 71
is only equal to that of a normal child at birth, the height has been
found above that of the latter, illustrating, as Fleischner remarks,
“that age plays some part in the growth of the infant, independent
of the weight ” This corresponds with the cases of the animals
already cited Fleischner concludes from his measurements of 500
children of whom 25 per cent were well nourished, 35 per cent fairly
well nourished, and 40 per cent poorly nourished
It is in the poorly nourished children that age plays its most important
part In the poorly nourished children, most of whom are probably
somewhat premature, when the weight is below normal, ail the measure¬
ments are correspondingly below normal The height and circumference of
the head reach the normal birth measurements a little ahead of the weight,
while the chest and abdomen are two months later in reaching the measure¬
ments of a normal child at birth When the weight is stationary the in¬
crease in the measurements is very small, depending upon the slight in¬
fluence which age has upon the growth of the mfant notwithstanding the
weight The measurements of infants of the same w T eight, notwithstanding
the age, are very similar, the small difference depending, as when the weight
of a child is stationaiy, upon the very slight influence of age upon growth
The final conclusion can be drawn that during the first year of life the
primary factor m the increase of the measurements of the body is steady,
consistent increase in the weight, the influence of age being secondary and
much less important *
SUSPENSION OF GROWTH ON A MAINTENANCE DIET
Early in the course of our investigation we noted that young
rats could remain in apparent good health while living on some of
the mixtures of isolated food-stuffs, without giving any evidence of
growth In some instances the animals ultimately declined and
died where the diet was not changed, but in numerous cases body-
weight, which we used as our guide, remained practically unchanged
or showed a minimal slow increase (cf Charts XXXVII, I/XIII,
and TXIV). The experiment showing the greatest growth under
these dietary conditions is recorded in Chart XXXVIII Other
investigators have met with this stationary condition and accepted
it as evidence of satisfactory nutritive equilibrium. We soon became,
convinced, however, that a diet which will not induce real growth
at the proper age is unquestionably defective from the standpoint of
perfect nutrition Furthermore, inasmuch as the ungrown rat has a
far smaller reserve of available energy and manifests the utilization
of a suitable diet both speedily and conspicuously by its measurable
changes in size, the animal becomes an exceptionally appropriate
subject at this early stage for the study of the nutritive requirement.
The most precise evidence which we can present at this time of
the stationary condition of the animals which we have stunted by
* 1 $ C Fleischner* Archives of Pediatrics, October 1906
72
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
the particular dietaries adopted is derived from measurements on
three young rats of the same litter maintained for 124 days without
noteworthy growth, on a diet of
Glutemn
Starch
Sugar
Agar
Salt mixture I
Lard
Per cent
18 o
14 5 to 34 5
15 o to 20 o
5 o
2 5
20 o to 4s o
The curves of growth of these animals as well as three others
from the same brood fed on mixed food or the milk-food mixture
(and showing a normal growth) are reproduced in Charts LXXXI,
LXXXII, LXXXIII, LXXXIV, LXXXV, and LXXXVI
The animals were killed at the age of 178 days and measurements
were made by Dr S Hatai, of the Wistar Institute The tabulated
data are given on the following page, together with a report from Dr
Hatai, to whom, as well as to Dr Donaldson, we are greatly indebted
for helpful cooperation
The statistics of body-length, weight of brain, spinal cord, etc ,
of the stunted animals at an age of 178 days are comparable with
those characteristic for normally growing rats of the same body-
weight, which is attained at an age of approximately 54 to 63 days
Here, then, are illustrations of maintenance without growth.
Dr. Hatai further reports as follows:
Since it seems to be[the least variable character, I have selected the body-
length as the basis for computation When the other characters which we
can measure are calculated from the formulas based on body-length, it is
seen that the observed weight of the brain and of the spinal cord agrees
closely with the calculated m both the control and the stunted rats Thus
both series have a growth of the nervous system normal to their body-
length In the control senes, the percentage of water observed in both the
brain and the spinal cord agrees with that calculated according to the body-
length In general then the control rats agree with the general population
in these characters Since the stunted rats have an abnormally small body-
length for their age, they can not be treated by the formula for determining
the percentage of water from body-length When, however, we take the
estimated percentage of water for 178 days (see Donaldson*) we find that
this value agrees with that observed in the stunted senes. It may be
further noted that the ratio between body-length and tail-length is the same
in both senes We therefore conclude that m both series the body-weight is
normal to the body-length, the brain and spinal cord weight normal to the body-
length, and the percentage of water normal for age. Concerning other organs
we have no data, but we may infer from the foregoing that they also have
weights normal to the body-length. You will see from the above that the
stunted rats though small have the general relative development of the
controls and that in the only case where it is possible to follow the matunng
process, that is in the percentage of water in the nervous system, they have
matured in accordance with their age (see Donaldson*).
"'Donaldson: Journal of Comparative Neurology, April 1911.
OSBORNE AND MENDEL
PLATE 1
A Rat 238, female Age 140 days, weight 144 grams, which is normal for a rat of same age as 240
B Rat 240, female Age 140 days, weight 55 grams* Same brood as Rat 238
C Rat 305 Age 36 days, weight 55 grams. Showing the appearance of a normal rat of same size as 240
A and B show the contrast between two rats of the same age, one of which (Rat 240) has been stunted.
The lower two pictures afford a comparison between two rats of the same weight, but widely differing m
age. The older, stunted rat, B, has not lost the characteristic proportions of the younger animal, C
OSBORNE AND MENDEL
PLATE 2
D
E
F
D Rat 168, male. Weight 235 grams, which is normal for a rat of the age of 220 shown below
E. Rat 220, male. Age 148 days, weight 58 grams.
F. Rat 305. Age 36 days, weight 55 grams. Showing appearance of a normal rat of same weight as 220.
D and E show the contrast between two rats of the same age, one of which (Rat 220} has been stunted
The stunted rat is not essentially altered m its bodily proportions from those of a much younger rat of
the same weight
SUSPENSION OP GROWTH ON A MAINTENANCE DIET.
73
Table XXXIV —Hatai’s Measurements or Stunted R vrs from Experiments of
Osborne and Mendel, 1910-191i.
Control Rats
Diet j
1
1 1
Sex
Milk !
Fem
Milk |
Fem
Mixed |
Male
| V* eight m grams of— 1
;4.geinl , Hypo-
days ,--physis
Percentage
of \\ ater
Length in
mm of—
Body I Brain Cord
- physis 1
* t
Brain Cord Bod> Tail
Rat q 6 Milk , Fern ! 178 154 91 73460 40340 0073 78 30671 130 176 146
Rat Q7 Milk j Fem 178 [164 51 60740 50070 000378 47371 220 183 - 164
Rat oo 1 Mixed | Male 178 j 175 0J1 85150 48100 0052178 6237! 800 181 144
j 1 - --;-,-1- 1 -
Average 1 ; 164 8,r 76120 40370 007178 46771 380 180 151
Calculated from body-length 1 76450 5004
Estimated percentage of ater from age* * ;
78 37471 192 180
7S 4 71 2 1
Body-length to tail-length 1 o 83
Stunted Rats
Rat 100 Glutenin Fem 178 ' 85 01 63230 40800 003578 14*70 775 148 1 120
Rat 101 Glutenin; Male j 178 j 71 81 50220 37810 0022 7S 27271 701 130 108
Rat 102 Glutenin! Male 178 ! 85 71 62800 30770 003378 133 71 134 148 125
Average ’ 1 80 8|i 58750 30200 003078 18271 203 145 121
I 1 'ill!,.'
Calculated from body-length ji 58960 3639 145
Estimated percentage of watcrfrom age 78 4 71 2
Body-length to tail-length 1 o 83
Formul is
Brain weight =0 569 log (io ^ OC * y * en S t h+ 1 34 _7)4.0 554
*43
Spinal cord weight=0 585 log (10
Body-length+134
-1- 6 )—o 795
Percentage of water (brain) =82 62—2 log (Body-weight— 10)
Percentage of water (spinal cord) =85 20—6 5 log (Body-weight)
Photographs of other rats which have been dwarfed in like ways
give evidence of the similarity of the stunts in general appearance
with normal animals of the same weight at a much earlier age. Thus,
inPlate i, rat 305, C, weighing 55 grams at the age of 36days, compares
favorably with rat 240, B, dwarfed on a gliadin food mixture, at the
age of 140 days, when it weighed 55 grams (cf. Chart CXIII). It is
interesting to contrast B with the uppermost photograph A of rat
238, likewise 140 days old and from the same brood but weighing
146 grams, the normal weight for this age. Bach was raised under
74
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
identical conditions from the age of 38 days, except that rat 238
(see Chart LVI) was fed with a paste containing casein and pro¬
tein-free milk, while in the food of 240 (see Chart CXIII) the casein
was replaced by gliadin.
Plate 2 shows rat 220, E, fed on gliadin and protein-free milk
but weighing only 58 grams, although 148 days old, and, for con¬
trast, rat 168, D, of approximately the size normal for the age of
rat 220, is also shown Figure F shows a normally nourished rat of
the same weight as rat 220 This picture is introduced to show that
rat 220 has the appearance of a normal rat of corresponding size and
weight All these pictures were taken on exactly the same scale and
afford a ready comparison of the relative sizes of the animals.
The interesting photographs of underfed cattle published by
Waters, on the contrary, make the change of form in his under¬
nourished animals of stationary weight quite apparent We are,
however, not prepared to assert that careful measurements of our
stunted rats will not disclose some trace of similar changes in skeletal
form. They must be slight at most, for we have often compared
animals long maintained at small stature with properly grown animals
which have just reached the same weight, without detecting any devi¬
ation from the youthful form in so far as one could judge by mere
visual inspection. The photographs speak in the same sense
The point on which we lay great stress in the foregoing experi¬
ments is the fact that the stunting is not attributable primarily to
under-feeding. Our dwarfed rats have as a rule eaten as adequately
as normally nourished animals of the same size The energy factor, as
such, thus drops out of the problem. In this respect the experiments
are not comparable with those of Waters and of Aron, both of whom
accomplished their results by underfeeding with adequate food mate¬
rials. In our experiments the ‘ * energy requirement for maintenance’ ’
and the “energy requirement for growth ” which together are essen¬
tial to the developing organism, were both supplied. The rats did not
grow primarily at the expense of stored tissue materials they failed
to grow in any sense We are obviously dealing with some other feature
than insufficient energy supply. The numerous illustrative experi¬
ments which will be cited later are accordingly to be in terpreted as
instances of maintenance without growth. If it is true that growth
can only continue when the energy intake exceeds the mere main¬
tenance requirement, it is equally true that an excess of calories does
not per se insure growth in a suitable animal Here then is the
opportunity to ascertain and differentiate some of the essential qual¬
itative factors: protein, inorganic salts, etc.—their minimrim an d
optimum values.
EFFECT OF STUNTING ON THE GROWTH IMPULSE-
75
EFFECT OF STUNTING ON THE GROWTH IMPULSE
Before proceeding to study the influence of dietary variations on
(a) maintenance and ( b ) growth, respectively, it became necessary to
learn whether a more or less temporary inhibition of growth checks
or in any degree modifies the capacity to grow (Wachstumstneb)
The literature on this subject by no means reveals a unanimity of
opinion, although familiar experience will bring to mind many iilus-
trations of compensated retardation of growth m children * A few
typical experiments may be cited Rat 36 (male) kept stunted 49
days on a diet of gliadm foodf (37 days) followed by casein food mix¬
ture! (12 days), showed complete recovery of growth on a mixed diet
(see Chart XCVI) The “mixed diet of our animals consists of dog
biscuit, sunflower seed, and fresh carrots (with occasional changes
and addition of lumps of rock salt) Rat 65 (female) stunted, during
33 dayson adiet ofcasein-zeinfood,! likewise resumed anormalrateof
growth as soon as the mixed diet was instituted (see Chart XXXVII).
Special interest is attached to experiments in which after a pre¬
liminary stunting period the resumption of growth was accomplished
on a diet containing milk as the effective component Two protocols
of the diet during the stunting period are reproduced m Table
XXXV, with reference likewise to Charts XXVIII and XXIX
Tvbix XXXV
Duration of stunting
Rat 64 (female),
33 days
Rat 5r (male),
40da>b
1
per cent
per cent .
Casein 12 0
Casein
18 0 1
*Zein 6 0
Starch
29 5
Starch 20 5 1
Sugar
15 0
Stunting diet
Sugar 15 0 1
Agar
5 0
1 Agar 5 0 1
I Salt mixture I 25
TSalt mixture I 25
[1 Lard 30 0
Lard
30 0
•“The zein was hydrated by the addition of a little water fCf , p 86
The curves in these cases are seen to be quite comparable with
those of the normally growing rats Bearing in mind that the animals
here studied were continually kept in small cages under actual experi¬
mental conditions, the “normal” character of the growth curves
makes it evident that the environment is no wise detrimental.
*Cf Condereau Recherches chimiques et physiologiques sur l’alimentation. des
enfants. Pans, 1869, Pagham Giornale della reale societa italxana d’igiene, Milano,
1879, x (Quoted by Hatai Amencan Journal of Physiology, 1907. xvxn, p 320 )
fSeep 122.
f See p. 98. Water was added to this mixture until the zein was well hydrated
76 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
Normal growth, as judged by curve of increase in body-weight,
was resumed on a diet consisting of
per cent
"Trunnlk” 60 o
Starch 16 7
Lard 23 3
Similar experiences are shown after feeding gliadin (Charts
XCIX, C) or edestin (Chart TXV)
In the case of rat 37 (Chart XCVII), a stunting period of 49
days on a diet of gliadin food for 37 days, followed by casein food mix¬
ture for 12 days, was followed by normal resumption of growth under
a dietary regime in which a period of feeding on the above milk-food
was alternated with mixed food. Judging by the typical character
of the curve of growth in this animal the two types of resuscitation
diet, though radically different in origin, are equally efficacious in
promoting growth The growth curve shows little deviation from its
usual course incidental to the changes in the dietary
It may be remarked that the early stunting does not neces¬
sarily impair the capacity to breed at a later period when growth is
again established Furthermore, we have found that the milk-fat-
starch mixture continued from early life in no wise impairs the
potency of rats as breeders Its nutritive efficiency will be referred
to again
Experiments such as those recorded above give unmistakable
evidence of the fact that a considerable period of stunting by no
means impairs the “ Wachstumstneb ” of these animals As soon
as an appropriate diet is instituted growth begins anew and proceeds
with practically the same speed as under normal conditions By this
we mean that a definite increment of gain from some fixed weight
requires approximately the same period for its accomplishment as m
the case of uninterrupted growth A rat which will ordinarily grow
from 60 grams to 180 grams in body-weight in 60 days will make the
same gain even when its growth has been inhibited days or even weeks
and its size and form retained at a maintenance level This will be
apparent by comparing, for example, the normal growth curve for
both male and female rats with that of the realimented rats, during
the same period of time, in Charts CXXII and CXXIII
It should be emphasized that the situation is here quite differ¬
ent from that developed by Waters and Aron in the experiments
on cattle and dogs. With their conditions of underfeeding the animals
increase in size (height, etc.) while starving; and during the earlier
period of such trials a poorly fed animal may actually gain in height
as rapidly as a highly nourished one, fed to the limit of its appetite.*
*Cf Waters The capacity of animals to grow under adverse conditions Proceedings
Society for the Promotion of Agricultural Science, 1908, xxix, p 15
EFFECT OF partial starvation on body-weight
77
The duration of the period of growth of the undernourished animal
depends upon the constitutional vigor of the individual and the store
of fat which it has accumulated. Quoting Aron “Dem Kinschmelz-
ungsprozess fallt neben dem Fettgewebe in erster Time die Musku-
latur zum Opfer, wahrend die Organe ihm widerstehen, wohl well
sie lebenswichtiger sind ”
The results of realimentation in animals which show this “dis¬
proportionate ’ ’ growth, i e , growth of one part at the expense of
another, are not yet satisfactorily ascertained Waters believes that
physiological compensation may result “by an increase in the rate of
growth in a period of liberal feeding following a period of low nourish¬
ment and low gain In other words, an animal that is below the
normal in size at a given age, through poor nourishment, apparently
has the capacity, when liberally fed, to compensate for this loss, in a
measure at least, by an increased rate of gam ” He also suggests the
possibility that growth may be accomplished on a more economical
basis—a view which we are not yet ready to accept
EFFECT OF PARTIAL STARVATION ON BODY-WEIGHT
Hatai* has studied the effect of partial starvation followed by
normal diet on the growth of white rats The “partial starvation”
consisted m feeding a diet that is practically devoid of protein, viz,
starch and water, during 21 days to animals about 40 days old The
realimentation was continued to the age of maturity, at the end of
200 days The statistics thus obtained and reproduced m Table
XXXVI are presented graphically m Chart XXVI
Table XXXVI— Hatai’s Measurements of Underfed and Re alimented Rats,
Bodj -weight
Ratio
-
—
Total
hctu eon
1
Initial
After
2t da>s
E mat
gain
initial
and final
1
, Male, controls
gm
gm
gm
1 gM
35 2
63 I
224
4
1S9 2
r 6 37
Male, experimented
37 6
28 4
242
0
204 4
6 43
Female, controls
36 3
67 8
11 ~2
6
136 3
4 75
Female, experimented
34 3
27 0
ii6?
8
133 5
4 89
Hatai concluded that, as far as body-weight is concerned, “the
experimented rats have completely recovered from the effect of 21
days of partial starvation The recovery in the weight is
most astonishing, especially during the first 3 or 4 days, within which
time the starved rats regain the weight lost during the 21 days of
starvation. Later the increase in weight is very steady, though not
as rapid as during the first few days, until the rat has reached the age
*Hatai American Journal of Physiology, 1907, xvrn, p. 310.
fThe body-weight in both control and experimented is small for the age.
78 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
of 150 days, and after this age increase in weight is relatively slow.
What will happen to such rats during the later portions of the span of
life has yet to be determined in order to answer the question whether
this partial starvation in early life has any influence either on
longevity or the onset of old age ” (p 314—315 )
EFFECT OF PARTIAL STARVATION ON NERVOUS SYSTEM
Though the period of retarded growth was eventually completely
compensated in Hatai’s animals, in so far as the weight of the body
and central nervous system are concerned, the chemical composition
of the brain and spinal cord was not entirely free from the effect As
the result of an extended investigation of the effects of underfeeding
on the nervous system, Donaldson* has arrived at the conclusion that
one of the characteristics of growth, the change in the water content
of the brain, has not been arrested like the increase of the animal m
size and body-weight, but apparently accelerated He states
The underfed group arc in this character similar to somewhat older ani¬
mals Evidence further points to the continued formation of the medullary
sheaths with advancing age even in rats which are underfed, i e , underfeed¬
ing does not arrest medullation Underfeeding which stops growth of the
body and retards that of the nervous system does not modify the percentage
of water m the spinal cord, while it does reduce it m the brain—the amount
of this reduction being less in the cases where the underfeeding is less severe t
With respect to the possible psychological effects of such under¬
feeding and return to normal diet Donaldson says.
So far as our tests show, such an experience does not modify the rat’s
ability to learn, for, by a senes of experiments, it has been possible to deter¬
mine that such a rat can learn to get its food under complicated conditions
just as well and as rapidly as a normal animal (Hayes) %
The preceding facts as to resuscitated rats are recorded here—
despite the fact that this temporary stunting was produced by under¬
feeding (rather than unsuitable feeding as in our experiments)—
because they suggest that the real story of the condition of the
animals may perhaps not be revealed by the external evidences of
growth. It is not at all impossible that the rats which we have
dwarfed for months may have experienced some continued subtle
changes in the make-up of the nervous system despite the appear¬
ance of unchanged youth which they manifest. Measurements of
size and weight alone may not suffice to disclose the real physio¬
logical status of the animal, especially in respect to the development
of the nervous functions and structures, which are singularly pro-
*Donaldson: Journal of Comparative Neurology, 19x1, 33a, p 139
T Donaldson tbtd., p. 169
{Donaldson Journal of Nervous and Mental Disease, 19x1, xxxvin, p. 262.
COMPARISON OP MIL,K AND MIXED DIET
79
tected even during starvation. This is seen to be true in the series
of stunted animals fed on the glutenin mixture in our experiments
(p 72). There is a large field of investigation still open here with
important bearings on the problems of retarded growth in man.
According to Donaldson* “the progressive diminution of the per¬
centage of water in the central nervous system with advancing age
is to be regarded as an index of fundamental chemical processes,
which take place in the more stable constituents of the nerve cells
These processes are but little modified by changes in the environment
and taken all together constitute a series of reactions which express
not only the intensity of the growth process in the nervous system,
but also the span of life characteristic for any given species ” Pos¬
sibly, then, the further study of the nervous system in connection
with our experiments may throw light on the phenomena of malnu¬
trition (which our stunting experiments primarily represent) as well
as those of undemutrition or starvation
It may be well here to note that the experience of Donaldson f
indicates the main features of human growth to be well represented
in the albino rat. So good is the essential correspondence that there
is every reason to continue the work on this form The striking
difference is that the rat grows some thirty times as rapidly as man.
COMPARISON OP MIEK AND MIXED DIET
The failure either to induce substantial growth in young rats or
to satisfy completely the maintenance requirement of older animals
during very long protracted periods on the mixtures of isolated food¬
stuffs thus far reported raises the question as to what constitutes an
ideal nutriment for a rat The suitability of mixed diet is beyond
question The favorable experiences with dried milk powder (some
of which have been recorded on pages 75 and 76) early directed our
attention to this product Rats were not only resuscitated after
nutritive decline and suitably maintained, but also grown from early
age on pastes in which the milk powder (with lard and starch) con¬
stituted the mixture The commercial brand ‘ * Trumilk employed
by us has been analyzed at the Connecticut Agricultural Experiment
Station with the following results
Per cent -
Water . 3 8
Total solids . . 96 2
Protein (NX6 38) . .25.6
Fat ... 27 4
Lactose ♦ . - • 37 2
Ash • . * . ,60
*Donaldson Journal of Comparative Neurology, 1910, xx, p„ 143
tCf Donaldson Journal of Nervous and Mental Disease, 1911, xxxvn, p. 258.
{This product was kindly furnished to us in powder form by the M errell-Soule Co.,
Syracuse, N. Y.
So
FEEDING EXPERIMENTS WITH ISOLATED POOD-SUBSTANCES
The preparation apparently contains a small excess of iron over
that found in cow’s milk—probably as a contamination from the
desiccating process used It is obtainable in easily manipulated form
and with the addition of a small amount of nitrogen-free lard and
starch forms a food paste readily consumed by rats. These pastes
have been used, either with or without our earlier standard salt
mixture (I),* as follows
Per cent
Per cent
“Trumilk , \
60 0
60 0
Starch
16 7
15 7
Lard
23 3
23 3
Salt mixture I
0 0
1 0
100 0
100 0
Nitrogen content
2 5
2 5
We have carried rats through the period of growth as well as
pregnancy on this diet alone, from the time that they were removed
from the mother (cf Charts XXXI, XXXII, and XXXIII)
As a further illustration of the excellent nutritive properties and
physiologically appropriate “combination” of food ingredients in the
milk food-mixture, illustrative charts are appended to show the re¬
covery of rats moribund after prolonged periods of malnutrition, with
lack of inorganic salts in the dietary (Charts XXXIV and XXXV)
Many similar illustrations might be reproduced, giving evidence of
the perfect realimentation of rats by the use of the milk food (cf
Charts XXVIII, TXV, XCIX, and C).
Remembering that ourearlier trials with casein, the chief protein
ingredient of the milk powder, and with combinations of casein and
other proteins were at best successful only in maintaining nutritive
equilibrium—and that not indefinitely—and were never adequate
for the manifestation of real growth, we directed our attention to the
non-protein constituents of milk After numerous failures to modify
the inorganic and non-protein ingredients of our dietaries by altering
the relation of proportions of the various ions as well as the character
of the carbohydrates and fats, it occurred to us that the protein-free
portion of the milk might give the clue to the successful feeding of pro¬
teins which did not appear to be the inefficient factors in our cases of
malnutrition. Accordingly a product was prepared as follows
Perfectly fresh centrifugated milk, nearly free from fat, was pre¬
cipitated in lots of about 36 liters by diluting with 7 liters of distilled
*This mixture, prepared in imitation of Rohmann’s successful product and empirically
found by use to be tbe most satisfactory of the different combinations tried, has the
following composition*
NaCI
Na citrate.
Grams
10 o Mg citrate
37 o Ca lactate
30 o Fe citrate.
15 o
Grams
8 o
8 o
a o
zoo o
(CL our previous report. Feeding experiments with isolated food-substances. Publi¬
cation No 156, Carnegie Institution of Washington, p 32 )
COMPARISON OP MILK AND MIXED DIET 81
water which contained i 64 c c of concentrated hydrochloric acid.
The flocculent precipitate of casein was strained out on cheesecloth
and the very nearly clear solution was filtered through a pulp filter
The filtrate, which at the most was very slightly turbid from sus¬
pended fat, was tested carefully by the alternate addition of dilute
alkali and acid to determine whether any more casein could be sepa¬
rated from it The addition of alkali caused a slight precipitate
which did not increase on adding more alkali or dissolve on the addi¬
tion of even relatively large amounts of alkali This was presumably
chiefly calcium phosphate The addition of acid in no case caused
any further precipitation The filtered milk serum was then heated
to boiling for a few minutes and filtered The filtrate, which was m
all cases water clear, was then neutralized to litmus with a dilute
solution of sodium hydroxide and evaporated to dryness on a steam
bath at a temperature of about 70°. The product thus obtained
formed a friable, pale yellow mass which was easily reduced to a fine
powder by grinding in a mill Several grams of this powder were
tested for protein by dissolving in about 30 c c of water containing
a little hydrochloric acid and warming gently The solution was then
saturated with ammonium sulphate The precipitate, which appeared
to consist chiefly of calcium sulphate, was separated by centrifugation,
dissolved in a little water, and potassium hydrate solution and copper
sulphate added The solution showed no evidence of the biuret
reaction until it was saturated with potassium hydroxide and shaken
with alcohol It then separated into two layers, the upper alcoholic
layer showing a slight but positive biuret reaction Millon’s reaction
tried on portions of 2 or 3 grams of the substance did not give a posi¬
tive reaction Nitrogen determinations m several lots of the protein-
free milk powder thus made showed them to contain o 66, o 59, o 60,
o 72, 071,0 67, o 75 per cent of nitrogen Munk* states that if the
proteins of milk are precipitated by alcohol, or separated according to
Hoppe-Seyler, from one-thirtieth to one-fifteenth of the protein
remains dissolved All the proteins can be precipitated only by
tannin in the cold or by copper hydroxide on heating He further
states that cow’s milk contains about one-sixteenth of its nitrogen in
non-protein form. Smce our protein-free milk powder was equal to
50 per cent of the total solids of the milk, it should, if Munk’s state¬
ments are correct, contain 0.48 per cent of non-protein nitrogen, thus
leaving at the most only 028 per cent of protein nitrogen, equal to
1.69 per cent of protein Since 100 grams of the food mixture
employed in our experiments contained 28 2 grams of protein-free
milk powder, we can assume that at the most the food pastes thus
made contained only o 48 per cent of milk protein. The protein-free
*Munk Virchow’s Archiv fur pathologische Anatomic, 1893, 134, p 501.
82 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
milk powder tlius produced as above described left about 14.5 per
cent of inorganic matter on ignition This includes not only the
inorganic constituents of the milk, although by no means in the com¬
bination in which they occur in the mammary secretion, but also the
inorganic salts which were formed by the addition of the hydrochloric
acid used to precipitate the casein and also the sodium salts which
resulted from neutralizing the milk serum with sodium hydroxide
solution.
EXPERIMENTS WITH ISOLATED PROTEINS AND *‘ PROTEIN-EREE * ’ MILK.
The use of this product (which we shall designate as protein-free
milk) as an adjuvant to isolated proteins to furnish the inorganic
elements of the diet has succeeded beyond our expectation. When
employed, for example, in combination with various proteins, in the
proportion in which its ingredients occur in the complete -miUr food
already used (see page 76), it induces normal growth. Added during
the periods of nutritive decline to food mixtures which no longer
suffice to maintain rats, recovery has manifested itself in practically
every case. Where, as in the case of zein, gliadin, or hordein feeding,
no advantage has been obtained by the use of the protein-free milk,
it has become obvious that the protein per se is the defective food
constituent Thus at length we have found a method of controlling
or furnishing some of the most essential non-protein factors m the
diet, so that the value of the individual proteins can be investigated
under much more favorable conditions than formerly
Numerous charts (see p 103 fig) present the graphic records
of feeding experiments with casein, edestin,* glutenin,* glycimn,*
gliadin,* hordein,* ovalbumin,f and lactalbumin, J showing appropri¬
ate growth, or maintenance, according to the age at which the anima ls
were started on the use of the protein-free milk as the non-protein
component in place of the earlier inorganic salt mixture
It might be objected, after superficial consideration of these re¬
sults, that the favorable outcome (especially for growth) is due to
milk protein contaminating the ‘ ‘ protein-free milk 5 ’ component of the
diet. Aside from the fact that the amount of possible contamination
is at most small, evidence of the untenability of such a theory is
available from several sources. In the first place, growth has not
followed the use of all proteins when the protein-free milk was added
to them.
1909, n, p 270
fThis was prepared by Hopkins’s method and was free from conalbumm Cf Osborne.
aj2< * Leavenworth American Journal of Physiology, iooq, xxxv, p. 252,
tTfae preparation of this is described on p 81.
ISOLATED PROTEINS AND ‘ ‘ PROTEIN-FREE ’ ’ MILK.
33
The results can be grouped in two series, viz
Diet = Isolated protein, protein-free milk, starch, agar, fat
Group I.—Young rats
Group II —Young rats
Active growth with—
Casein (Charts xwi, xlvii, lii, tin,
liv, i,v, i/VT, lvii, 1,vm, ux, and i,x
Ovalbumin (Charts xc and xci)
Lactalbumm (Charts xcn and xcm)
Edestm (Charts lxxi, lxxii, lxxiii,
i/xxiv, l,xxv, and lxxvi)
Glutemn (Charts i^xxxvn, lxxxviii,
and ivxxxix)
Glycimn (Charts xciv and xcv)
Little or no growth with—
Ghadin (Charts cvm, cix, cx, cxi,
cxu, cxnr and cxiv)
Hordein (Charts cxxxv and cxxv)
The failures in group n lead to the conclusion that the proteins,
ghadin and hordein, are inadequate for the functions of growth We
are presumably dealing with a chemical inadequacy rather than any
toxicity and consequent lack of growth, judging by the fact that the
gliadin and hordein rats are maintained in good, nutritive condition
even in the absence of growth Their body-weight is scarcely changed
at all Without the use of the protein-free milk or fseces-feedmg
gliadin rats have usually declined (Charts XCVIII, XCIX, and C)
A second reason why the success of these trials is not due to the
presence of possible minute contaminations with milk protein is
discoverable in Charts XUII, XTIV, XLV, XLVIII, XLIX, T, U,
CVIII, CIX, CX, and CXI Here the addition of not inconsiderable
portions (5 to 30 per cent) of the actual milk food to the earlier
inefficient protein mixtures is incapable of bringing about growth in
any degree equal to that at once initiated when the protein-free milk
is added in relative abundance
Further evidence that a trace of milk proteins is not responsible
for the growth of the rats fed with mixtures containing our protein-
free milk powder is furnished by experiments in which successively
larger quantities of the milk food are added to the ghadin food. Here
we see that growth gradually increases with the larger additions of
the milk food, although with even as much as 30 per cent in the food
the rate of growth is much below normal. With additions of 5 or
even 20 per cent of the milk food, the rate of growth is very slow, as
shown by Charts CIV, CV, CVI, and CVII That this result is to be
attributed to the proteins introduced in the milk food and not to a
combination of a small quantity of milk proteins together with a
sufficient quantity of the inorganic or other constituents of the milk
is shown by experiments now in progress in which the addition of the
milk food to the gliadin and protein-free milk food is producing
normal growth. In this mixture we have all of the constituents of
84 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
the protein-free milk present in the same proportions as m our milk
food, but less than one-third of the protein constituents of the milk
It is therefore evident that only a small proportion of the protein
constituents of the milk are required to produce normal growth, and
it may be assumed that the presence of a small quantity of milk
proteins m our protein-free milk powder would manifest itself by at
least some slight growth
DISCUSSION OF THE RESUETS AND THEIR BEARINGS
We have stated that by our plan a biological comparison of dif¬
ferent proteins in respect to their r 61 e in growth can at length be
made. Our work in this direction must be regarded as barely begun.
Nevertheless it is of interest to speculate as to the indications already
gained and the outlook for future work. A comparison of the two
groups of proteins—those adequate and those inadequate for growth
purposes—at once reveals the fact that the latter category comprises
proteins (gliadm, hordein, zein) commonly spoken of as chemically
“incomplete ” They lack one or more of the ammo-acid complexes
which are obtainable from the so-called “ complete ” proteins None
of them furnish glycocoll or lysine, and zein in addition is devoid of
tryptophane. By feeding relatively small quantities of proteins like
casein with gliadin growth begins at once Here we can determine
the minimum of suitable protein to satisfy this growth requirement—
a study already begun (cf Charts CXX, CXXI, CXXII, and
CXXIII). The addition of amino-acids to “complete,” as it were,
the inadequate proteins can now be studied amid controllable factors,
the biological r 61 e of hydrolyzed proteins and the significance of
complete hydrolysis or digestion in nutrition can be examined anew.
The experiences which have demonstrated the striking differ¬
ences m value of the individual proteins and the small proportion of
casein which suffices to induce growth instead of standstill (cf Charts
CXX, CXI, CXXII, and CXXIII, for example) emphasize the impor¬
tance of the purity of the protein fed We have devoted much labor
and incurred a very considerable expense to obtain proteins in a form
as uncontaminated as present methods will permit The products
used were as pure as one would expect th em to be if employed for
purposes of refined protein analysis. Had less perfect products been
employed it is quite conceivable and indeed likely that the admix¬
tures would have sufficed to alter completely the outcome of many
experiments For example, gliadin is prepared free from glutemn
only be very careful purification methods; and although the nutritive
properties of these two companion proteins are extremely unlike, as
clearly indicated by our trials, a failure to effect a complete separa¬
tion of a little glutenin from gliadin would have been sufficient to
prevent the deficiencies of the latter from exhibiting themselves. Or
DISCUSSION OK THIS RBSUIyTS AND TH^IR BEARINGS
85
again, failure to purify carefully a protein like casein will vitiate the
study of a problem like the synthesis of amino-acids Pure casein is
glycocoll-free, and the continued feeding of such a product as the
sole protein of the dietary enables one to make deductions respecting
the synthesis of glycocoll The use of crude commercial protein
preparations can never satisfy the requirements of refined study in
this domain, where small effects continued over long periods are of
great importance We believe, therefore, that such considerations
justify the energy and expense which have been put into the work
In relation to the much-discussed problem of the relative value
of organic vs inorganic phosphorus in nutrition, our data after feed¬
ing phosphorus-free edestin to growing rats (cf Charts LXXV and
LXXVI) show a success quite as great as that with phosphorus-con¬
taining casein (cf Charts TVI, I/VII, I*VIII, LIX, and LX) The
animals must here have synthesized their phosphorus compounds
from inorganic phosphorus "Whether milk production and other
functions calling for such synthetic reactions will continue adequately
is open to investigation It is also noteworthy that all of our animals
grow on a dietary that is punne-free, or essentially so Here the ques¬
tion of purine synthesis suggests itself It is apparent, eg, in the
case of gliadin, that the grown as well as ungrown rats may be
ta'ined for long periods on single proteins
"With such an ideal non-protein dietary component at hand
amino-acid substitutions can be attempted in the adult as well as in
the growing animal The protein minimum (or minima) is also open
to accurate investigation With a method of feeding devised which
will permit a differentiation between growth and maintenance, which
furnishes an energy-yielding protein-free component that is appro¬
priate, and leaves the protein as the sole variable in the dietary, we
believe that further contributions can be made to the problems of
nutrition
In the preparation of the large quantities of carefully purified
proteins required for these experiments, we have been assisted by
Mr Charles S Leavenworth, Mr. Owen Nolan, Mr Teigh I Hol-
dredge, and Mr. Lawrence Nolan, whose valuable cooperation we
are glad to acknowledge here
86
FEEDING EXPERIMENTS WITH ISOEATED FOOD-SUBSTANCES.
THE CHARTS AND THEIR EXPLANATIONS.
In the following charts, to which reference is made in various
places m the text, the abscissae of the curves represent days and the
ordinates actual body-weight (solid line) or food-intake (dotted line)
in grams In some of the charts the average (normal) curve of
growth, plotted from body-weight data available for normally grow¬
ing animals of the same sex, is represented by a broken line for com¬
parison Xhe food-intake curve is plotted from the quantities of food
eaten per week. Xhe numbers on the body-weight curves indicate
the time at which changes in the character of the feed in g were insti¬
tuted All curves in this paper are plotted on the same scale, so that
they are directly comparable
Salt mixture I, to which reference is frequently made, was
composed of—
Ca 3 (P04)2
Grams
10 0
K2HPO4
37 0
NaCl
20 0
Na citrate
i 5 0
Mg citrate
8 0
Ca lactate
8 0
Fe citrate
2 0
100 0
INDEX OF CHARTS WITH REFERENCE TO FOOD-MIXTURES AND
PROTEINS FED
[Numbers refer to
Casern, 93, 96, 97, 99 * 100, ioi, 103, 104,
105, 106, 107, xo8, 122, 123, 133, 134
Casein-hglutenin, 94
Casein+legumin, 97
Casem+milk, 102, 104
Casein-f-zein, 92, 98
Edestin, 109, no, in, 112, 113, 114, 115,
116, 117
Edestin-j-mi Ik, 112, 113
Feces, 99, 100, xoi, no, 111,115*225,126
Gliadin, 122, 123, 124, 125, 126, 128, 129,
130, 131, 132, 133, 134
Gliadm 4 -milk, 127, 128
Glutexun, 94, 119, 120
Glntemn -f-edestra, 94
pages in the text ]
Glycimn, 121.
Hempseed, 91
Hordern, 135
Lactalbumin, 121
Milk, 92, 93, 95, 96, 97, 109, 118, 123, 124
Mixed food, 87, 88, 89* 90, 94* 96, 97* 98,
99 * 100, 101, xo6, 108, 112, 115, 116,
IX 7» 118, X22, 123, 125, 126, 130, 131,
132, 136, 137, 138
Ovalbumin, 120
Protein-free milk, 94, 101, 103, 104, 105,
106, 107, 108, 112, 113, 114, 115, 116,
117, 120, lai, 128, 129, 130, 131, 132
133* 134* 135, 137, 138
Zein, 136, 137, 138
CHARTS AND THEIR EXPLANATIONS S7
Ch\rt XXII
Chart XXII shows average normal rates of growth of male and female white
rats according to Donaldson and to Osborne and Mendel. In our experience the
female rat does not attain as large a size as m Donaldson’s experiments. The growth
curves coincide until the animals reach an age of about 70 days.
100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400
Days
88
200 220 240 260 280 300 320 340 360 380 400 420 440 460
Days
CHARTS AND THEIR EXPLANATIONS. 89
Chart XXIII (rat 48, male) shows the growth of the mal e rat from
early life, under cage conditions adopted for experimental feeding The
animal was fed 452 days on mixed food, consisting of dog-biscuit, sunflower
and other seeds, fresh vegetables, and salt
Chart XXIV
Charts XXIV (rat 166, female) and XXV (rat 156, female) show the
typical growth of female rats, including pregnancy, under cage conditions
The animals were fed on mixed food
Chart XXV
9<
FEEDING EXPERIMENTS WITH ISOI^ATEjI> EOOD-SUBSTANCES
CHARTS AND THEIR EXPLANATIONS
91
Chart XXVII
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92
DEEDING EXPERIMENTS WITH ISOLATED ROOD-SUBSTANCES
Chart XXVIII
o 2 52 ^ TS
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CHARTS AND THEIR EXPLANATIONS
Chart XXIX
93
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CHARTS AND THEIR EXPLANATIONS
95
Chart XXX (rat 71, male) shows long-continued feeding of isolated
foodstuffs and also long-continued maintenance on glutemn from wheat as the
only protein The history of the animal is on p 59 The diets were as follows
Constituents
Per 1
Per 2
Pei 3
Per 4
1 Periods '
| sand 8 |
Glutenin
p ct
6 0
t> ct
6 0
p ct
16 36
p ct
iS 0
i p a 1
18 0 ;
Casein
12 0
12 0
0 0
0 0
' 00!
Starch
29 s
24 5
22 27
1 14 S
34 5
Sugar
IS 0
IS 0
13 63
| 15 0
’ 20 0 1
Agar
5 0
5 O
4 54
! 5 0
5 0 i
Salt mixture I
2 5
2 5
2 27
! 2 s
■ 2 S j
Lard
30 0
35 0
1 4° 9 ^
! 45 0
20 0
Constituents
Per 6
Per 7 j
[ Constituents
1
' Per 9 |
p ct
1
I
p ct
Glutemn
9 0
Mixed!
Glutemn
18 0 |
Kdestm
9 0
food j
Protein-free milk
1 28 2 •
Starch
33 5
j
Starch
23 s j
Sugar
18 5
Agar
5 0 ,
Agar
5 0
!
Lard
1 25 0
Salt mixture I
2 5
Lard
23 5
1 1
Chart XXX further shows the possibility of maintaining an animal
satisfactorily under our cage conditions for 458 days Attention is particu¬
larly directed to period 9, during which the only change m the diet consisted
m substituting protein-free milk for some of the non-protein components
of the dietary The lowest line represents the nitrogen balance of the rat
Chart XXXI
Ch\rt XXXII
Chart XXXI (rat 222, male) shows early growth curve of male on milk
diet, having the following composition* Trumilk, 60 o p ct.; starch, 15 7 p
ct , salt mixture I, 1 o p. ct , lard, 23 3 p ct.
Chart XXXII (rat 195, male) shows normal growth curve of male on
milk diet, having the following composition* Tru milk , 60 p. ct ; starch, 167
p. ct., lard, 23 3 p. ct.
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
Chart XXXIII
Chart XXXIII (rat 181, female) shows growth and normal pregnancy
of female on milk food, consisting of Trumilk, 60 p ct , starch, 15 7 p ct ;
salt mixture I, 1 o p ct , lard, 23 3 p ct
Chart XXXIV
_ Chart XXX IV (rat 106, male) shows malnutrition induced by lack of
inorganic salts In the dietary and subsequent perfect recovery on milk-paste.
The diet was mixed food for period 1; for the remaining periods as follows
Constituents
Casern
Starch.
Sugar
Agar
Salt mixture I
p. ct.
18
25 to 32 5
17 29 5
o 50
o 00
i P ct
I 18 o
1 32 5
j 219
I o o
! a 6
25 o
Constituents
Trumilk
Starch
Salt mixture I
Lard
CHARTS AND THRIR EXPLANATIONS
97
Chaet XXXV
Chart XXXV (rat i io, female) shows malnutrition induced by lack of
inorganic salts in the dietary and subsequent perfect recovery on milk-paste
The diet consisted of mixed food for period i, and as follows for the remain¬
ing periods*
Constituents
Per 2
Per 3 ;
Constituents
Per 4 j
p ct
p ct
P Ct ,
Casein
18
18 0
Trumilk
60 0
Starch
25 to 32 5
32 5
Starch
15 7
Sugar
17 29 s
21 g
Salt mixture I
1 0
Agar
Salt mixture I
0 50
0
0 0
2 6
Lard
1 23 3
Lard 1
20 35 0
25 0
’
,
Chart XXXVI
30
8
idy weifi
ht } „
em food
'""I
E
3
*00
at
-j
c
55
m
3
20 40
Days
dead,
cause
unknown
60
Chart XXXVI (rat 54, male) shows the
maintenance for 46 days of a very small rat,
without growth, on a diet in which casein
formed the sole protein The composition of
the food was as shown herewith
Constituents
Per 1
Per 2
Casern
p ct
xS 0
p ct
9 0
Pea legumm
0 0
9 0 i
Starch
29 5
29 S
Sugar
IS 0
15 0
Agar
5 0
5 0
Salt mixture I
2 S
2 5
Lard
30 0
30 O
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
Chart XXXVII (rat 65, female) shows stunting for 33
days during early life, followed by normal growth and preg- Casem
nancy on mixed food. In addition to the typical growth iSSrth.
during 317 days, the curve emphasizes the unaltered “ca- ®“« ar
pacity to grow” after stunting by improper diet. The diet ssStxnixturei
during period 1 was as shown herewith. I ' ard
Chart XXXVIII
(rat 50) shows main¬
tenance for 158 days
on a diet in which
casein formed the sole
protein. The com¬
position of the food
was as shown here¬
with*
20 40
120 140
Days
ISO 200 220 240
Chart XXXIX (rat 145, female) shows the effect p . ds ,_. d ,
of feeding a diet of isolated food substances in which . %. a.
casein formed the sole protein. Period 1 represents Starch % 5 ; *
the normal growth of the animal on a mixed food, su gar ... « 9 to 26 9
The casein feeding began with period 2. The influ- Sait mixturei.‘ 35 a 6
ence of faeces of normally fed animals in preventing Lard . 30 0 35 0
decline in body-weight is shown during period 3. As shown by the food
intake, the favorable effect is not due to an increased consumption of food.
The diet during period 1 consisted of mixed food; during periods 2 and 3
as shown in table.
zoo
feeding experiments with isolated eood-substancbs
Chart XL
0 20 40 60 80 100 120 140 160 180 200 220 240 260
Days
Chart XI/ (rat 150, female) shows the influence
of a diet containing a mixture of isolated foodstuffs
in which casein was the sole protein. Period 1 repre¬
sents the normal growth of the animal on a mixed
food The casern feeding began with period 2 The
influence of faeces of normally fed animals in prevent¬
ing decline m body-weight is shown during period 3
Periods 2 and 3
p ct
Casein 18 o
Starch 32 5
Sugar 21 9 to 26 9
Agar 00 so
Salt mixture I 25 26
Lard 20 o 25 o
As shown by the food
intake the favorable effect is not due to an increased consumption of food.
The diet during period i consisted of mixed food, during periods 2 and 3 as
shown herewith.
Chart XI/I (rat 127, male) shows the influence of a diet containing a
mixture of isolated foodstuffs in which casern was the sole protein Period 1
represents the normal growth of the animal on a mixed food The casein
feeding began with period 2 The influence of faeces of normally fed animals
in preventing for a time the decline in body-weight is shown during period 3.
Period 4 shows the favorable nutritive influence of the substitution of
protein-free milk for a part of the non-protein constituents of the diet. The
diet during period 1 consisted of mixed food. During periods 2, 3, and 4
the composition of the food was as shown herewith.
Constituents
Periods
2 and 3
Constituents
Per 4
PaCAITl
Starch
Sugar
Salt mixture I .
Lard - ,
p ct
18 0
32 5
21 9 to 26.9
2 6
20 O 25 0
Casern. , , .
Protein-free milk
Starch . .
Agar .
Lard *. , ,
P ct
18 0
28 2
23 8
5 0
25 O
CHARTS AND THEIR EXPLANATIONS.
IOI
Chart XLI
270
250
230
210
190
170
80
60
40
/v
m
hi
\
m
m
m
/
\
Boc
y weigh
m
m
m
Sj
m
m
f
\
f
m
—
H
■
e—M ixed
food-x
Casein \
■
H
■ I
HH
mmm
■
■
■
■
H
■
m
m
BP
m
HI
H
m
m
m
m
■
H
■
m
m
m
IB
m
m
20
40
60
80
100
120 140
Days
160
180
200
220
240
260
Chart Xlyll (rat 103, male) shows the influ¬
ence of a diet of isolated food-stuffs containing
casein as the sole protein. The satisfactory pre¬
vious nutritive condition of the animal is shown
during period 1 on mixed food. Casein feeding
was begun with period 2; and the favorable
effect of faeces of normally fed animals is shown
during period 3. The composition of the food
in periods 2 and 3 was as shown in table.
PagAin
Starch
Sugar
Agar
Salt mixture
Lard.
p ct .
18 00
as 00 to 32 So
12 87 25 37
o 00 5 00
4 13
SO OO 35 00
The salt mixture, which was prepared
for other purposes, consisted of the
citrates of calcium, magnesium,
sodium, potassium, and iron, and the
chlorides of sodium and potassium.
102
FEEniNQ BXP^RIMKNTS WITH ISOLATED EOOID-STJB STANCES.
Chart XXV
Charts XLIII (rat 231, female),
XLIV (rat 230, male), and. XLV (rat
223, male) show the effect of succes¬
sive additions of increasing quantities
of milk powder to the usual casern
diet "The smaller quantities of milk
are insufficient to induce normal
growth. The diet during the several
periods was as follows
Constituents
Per I
Per 2
Per 3
♦Casern food
P ct
P ct
p- ct
95
80
70
fMilfcfood . .
5
20
30
* Casein food* casein. 18 o, starch, 325.
sugar 17 0, agar, 5 o_ salt mixture I. 2 5, lard, 25
TMjIIc food Tinisiilk, 60 o; starch, 15 7,
salt mixture I, t o, lard, 23 3
CHARTS AND THEIR EXPLANATIONS.
IO3
Chart XLVI.
Chart'XLVII
Charts XLVI (rat 177, female) and
XLVII (rat 191, male) show mainte¬
nance on a diet in which casein formed
the sole protein during 83 days followed
by growth when protein-free milk was
substituted for a part of the non-protein
constituents of the diet The diet was
as shown herewith.
Constituents
Per 1
Per 2
Casein
p ct
18 0
p ct
18 0
Protein-free milk
0 0
28 2
Starch
32 5
23 8
Sugar
17 OtO 20 0
0 0
Agar
5 0
5 0
Salt mixture I
2 s
Q 0
Lard
22 0 25 0
25 0
104
FEEDING experiments with isolated food-substances.
Cham XXVIII. Chart XXIX
0 20 40 60 80 100 120 140
Days
Charts XLVIII (rat 210, female),
XLIX (rat 209, male), L (rat 215, male),
and LI (rat 216, male) show inadequate
growth, during period 1, on the casein
food with a small admixture of milk, fol¬
lowed by resumption of growth on a diet
containing casein and protein-free milk in
a quantity equivalent to that of our milk-
paste diet which has proved sufficient to
promote normal growth. The compo¬
sition of the food was as shown in table.
Chart X,
Chart JJX
CHARTS AND THEIR EXPLANATIONS.
Chart lit
msssui
Chart LI II
Charts UI (rat 205, female)
and LIU (rat 207, female) show
imtiation of favorable growth
when protein-free milk is added
to a dietary containing casein as
its sole protein in period 2. In
the preliminary period an unsuc¬
cessful attempt was made to in¬
duce growth by feeding different
proteins in rotation. The diet
was as shown in table.
Constituents
Casein or )
Edestin or \
Gliadin ]
Starch
Sugar
Agar
Salt mixture I
Lard
120
140
r
Per 1
1
Constituents i
Per 2
i> a !
p ct
Casern
18 0
28 0
Protein-free milk
28 2
Starch
23 8
32 s
Agar
5 0
17 0
Lard
25 0
5 0
2 5
25 0
io6 feeding experiments with isolated pood-substances.
Chart LV
Chart LIV (rat 204, female) shows uninterrupted Periods
growth when a diet of isolated food-stuffs containing casern
^sem as its sole protein was substituted for mixed food. g^- £reenulk *}
The requisite inorganic salts were furnished in the added s 0
protein-free milk. The experiment is of exceptional inter- 250
est inasmuch as the animal successfully passed through two periods of
pregnancy on a purine-free foodcontaining a single protein. This obviously
affords a method of studying various synthetic processes in the animal body.
The diet during period 1 consisted of mixed food During period 2 as shown
Chart DV (rat 203, male) shows uninterrupted
growth when a diet of isolated foodstuffs containing
casern as its sole protein was substituted for food
The requisite inorganic salts were furnished in the added
proton-free milk. The diet during period 1 consisted of
mixed food; during period 2, as shown herewith.
Period 2
pa
Casein 18 o
Protein-free "iillr 28 a
Starch . . 23 8
Agar . . so
Ifitd , as 0
trams
K
Casem-r Protein-free milk
A Casein+Protein-free milk-—
Casem +Prote i rirfree milk
Food eaten
Charts I/VI (rat 238, female), LVII (rat 269, female), LVIII (rat 247,
male), LIX (rat 252, male), and LX (rat 2 68, male) show p a
normal growth on a diet containing a single protein, ca- ca«m . . ig o
sein. The requisite inorganic salts were furnished in the staxSf. * ^ I
added protein-free milk. This experiment illustrates arti- 2 | °
fidal nutrition with isolated food-substances from a very-
early period of life. The diet was as shown herewith.
108 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
Chart £<XI
CHARTS AND THEIR EXPLANATIONS.
109
Charts LXI (rat 141 > female) and LXI I (rat 139, male) show recovery
of animals maintained on a diet conta inin g casein as the sole protem The
preliminary nutritive condition of the rats is shown to be satisfactory m
period 1 on a mixed diet The ultimate decline on the casern diet during
period 2 could not be checked by increasing the content of casein during
period 3 This shows that the nutritive failure of the animals was not
attributable to the protein per se. Speedy recuperation and m ain t enan ce
attended the substitution of protein-
free milk for the inorganic salt mix¬
ture contained in food previously used
Note the influence of this dietary
change on the appetite of the an imals
In period 1 mixed food was used. The
composition of food, during the other
periods was as shown m table.
Cham LXIII.
Constituents
i
2
Per 3
Per 4
1 p Cl
P ct
p ct
Casein
18 0
36 0
18 0
Protein-free milk 0 0
0 0
28 2
Starch
32 5
22 5
23 8
Sugar
21 9 to 26 9
13 9
0 0
Agar
0 0
5 0
0 0
. 5 0
Salt mixture 1
‘ 2 s
2 6
2 6
1 0 0
Lard
20 0
25 0
25 0
! 25 0
Chart LXIV
Charts LXIII (rat 60, male) and LXIV (rat 58, female) show
maintenance and slight growth of a rat on a diet m which edestin
constituted the sole protem for 67 days The experiment was ter¬
minated because of the death of another ammal, which was found
partly eaten, in the same cage. The diet was as shown herewith
Edestin
p ct
18 0
Starch
29 5
Sugar
15 0
Agar
5 0
Salt mixture I
2 5
Lard
30 0
Chart LXV
Chart LXV (rat 189, female) shows
failure of rat to grow or be maintained on
a diet containing edestin as the sole pro¬
tein during 72 days (period 1) There is
no loss of capacity to grow, as will be seen
by the curve of growth on the milk- diet in
period 2, 32 days The diet consisted of—
Period z
p ct
Edestin
18 0
Starch
29 5
Sugar
IS 0
Agas
5 0
Salt mixture I
* 2 5
Lard
Period 2
30 O
Tnunilk
60 O
Starch .
IS 7
Salt mixture I
.
. «• 10
CELAS.T LXVII
CHARTS AND THEIR B30PI<A2SrATrOMS.
zzz
Chart LXVm.
Charts XyXVIII (rat 196, female) and I^XIX
(rat 193, female) sliow maintenance on a diet 1x1
winch, edestin formed the sole protein The influ¬
ence of faeces of normally fed animals in preventing
decline in body-weight is shown during period 2
T'he giving of faeces was discontinued during period
3. T'he faeces were obtained from normally fed rats temporarily intro¬
duced into the cage each day. T'he diet is given above
Edestin
Starch
Sugar
Agar
Salt mixture X
Z*ard
i> ct
18 o
29 5 to 32 5
IS o 17 o
5 o
2 5
25 o 30 o
Chart LXIX.
M
PI
i
Hi
0|
a
a
0
0
hi
Hi
Hi
HE
m
Hi
Hi
iH
Hi
a
HU
HI
iH
IH
Hi
Hi
a
a
in
Hi
0|
HB
a
Hi
a
SHI
iHH
Hi
a
a
a
a
j|
0
|
Hi
a
0
|
HI
ia
a
0
LMW|
s
BWI
1 Kbb
O 20 4-0 60 80 IOO 120 140 160 180
Days
112
FADING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
Chart ZXK
Period 2
Edestin
Starch
Sugar
Agar
Salt mixture I
Eard
p ct
18 o
29 5 to 32 5
IS o 17 0
S o
2 5
25 0 30 0
Chart LXX (rat 133, female) shows mainte¬
nance on a diet in which edestin was the sole protein
during 161 days. Period 1 on a mixed diet shows
normal growth Period 2 is of interest because the
food was also purine-free and devoid of organically
combmed phosphorus All growth ceased during the
edestin feeding (period 2), m contrast with other experiences where protein-
free milk was present in the dietary
Chart I/XXI (rat 218, female) shows inadequate growth on a diet
of edestin+milk-paste (period 1) followed by growth during period 2,
m which the food contained pro¬
tein-free milk and edestin as its
sole protein. In growing to several
times its original weight the animal
must have synthesized its purine-
and phosphorus-containing com¬
plexes from purine-free food The
influence of size on food require¬
ment is shown by the food-intake
curve. The diet consisted of—
Chart LXXI
Period 1
Edestin food (edestin, 18 o, starch,
32 5 sugar, 17 0, agar, 5 o, salt
mixture I, 2 5, lard, 25 o)
Milk food (Trumilk, 60 0, starch 15 7 *
salt mixture I, 1 0, lard, 23 3 )
Period 2.
Edestin
Protein-free milk
Starch
Agar
Lard
p ct
90
10
18 0
28 2
23 8
S 0
25 o
CHARTS AND THSER EXPLANATIONS
“3
Chart LXXrV
Chart LXXIL
/
/
_ 1
J/
P/ 6°
T
4
/
1 * r
Food e
c
3
1 /
%
2
1 J
\ f
✓
r
/
1
,Edestin
Milk
/
r 00d 9Q%
« " 10%
- 1
yc Edes
»tin + Pro
_□
tem-fre
e nmln ;
0 20 40 60 80 100 120
Day s
Chart LXXIII
Charts kXXII (rat 217, male),
LXXIII (rat 211, male), and LXXIV
(rat 212, male) show inadequate growth
on a diet of edestm+milk-paste (period
1) followed by growth during period 2,
in which the food contained protein-
free milk and edestm as its sole pro¬
tein It should be noted that the ani¬
mals in growing to several times their
original weight must have synthesized
their punne- and phosphorus-containing
complexes from punne-free food The
influence of size on the food require¬
ment is shown by the food intake curve
The diet consisted of—
Period 1 $ cl
Edestm food (edestm, 18 o, starch, 32 5.
sugar, 17 0, agar, 5 o, salt mixture I, 2 5*
lard, 25 0) 00 0
Milk food (Trumilk, 60 0, starch, 15 7,
salt mixture I, I 0, lard,, 23 3) 10 0
Period 2
Edestm 18 0
Protein-free milk 28 2
Starch 23 8
Agar . s 0
Lard . 25 0
114
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
Chart LXXV.
C har t I/XXVT*
Charts LXXV (rat 248, female) and LXXVI (rat p et
253, female) show growth from an early age on a diet Edestm if o
contammg prot ein -free milk in which edestm formed the starch 23 :
sole protein It should be noted that the animals in a | ®
growing to several times their original weight must have
synthesized their purine- and phosphorus-containing complexes from punne-
free food The influence of size on the food requirement is shown by the
food-intake curve. The diet was as shown herewith.
Chart I/XXVII (rat 114, male) shows the failure of edestin (period 2)
to m aintain previous satisfactory nutritive condition of the animal during
penod 1, on mixed food, even after adding faeces to the diet (period 3)
Immediate improvement and satisfactory nutritive condition followed addi¬
tion of protein-free milk to edestin food (period 4). The diet consisted of
mixed food for period 1, and for periods 2, 3, and 4 was as shown in table.
Constituents
Periods
2 and 3
Edestin
p. ct.
18 0
Starch
■ 29 5 to 32 s
Sugar
15 0 17 0
Agar
5 0
2 S
Lard
25 0 30 0
Constituents
Per 4
Edestin
p ct
18 0
Protein-free milk
28 2
Starch
23 8
Agar .
5 0
Lard
25 0
Chart TXXVIII (rat 140, female)
shows the failure of maintenance on a diet
in which edestin formed the sole protein
(period 2), until protein-free milk was
added to the diet (period 3). Period 1,
on mixed food, is introduced to show the
previous satisfactory nutritive condition
of the animal. The diet consisted of
mixed food for period 1, and for periods 2 and 3 it was as shown in table.
Constituents
Per 2
Per 3
Edestin
p ct
18 0
p ct .
xS 0
Protem-free milk .
0 0
28 2
Starch
29 5 to 32 5
23 8
Sugar., ...
15 0 17 0
0 0
Agar .
5 0
5 0
Salt mixture I
2 5
0 0
Lard .
25 0 30 0
25 0
Grams
n6
FEEDING EXPERIMENTS WITH ISOLATED EOOlD-STJBSTAlsrCES.
Chart LXXIX
Chart lyXXIX (rat 152, female) shows the failure of maintenance on
a diet in which edestin formed the sole protein (period 2), until protein-
free milk was added to the diet (period. 3) Period 1, on mixed food, is
introduced to show the previous satisfactory nutritive condition of the
animal. The diet consisted of mixed food for period 1 and for periods 2
and 3 was as follows:
Constituents
Per 2
Per 3
Edestin
■p ct
18 0
p ct
x8 0
Protem-£ree milk
0 0
28 2
Starch.
S to 32 5
23 8
Sugar
15 O 17 0
0 0
Agar
Salt mixture I
5 O
a S
s 0
0 0
Eard
25 0 30 0
25 0
CHARTS AND THEIR EXPLANATIONS
117
Chart LXXX
milk was added to the diet (penod 3). Period 1, on mixed food, is intro¬
duced to show the previous satisfactory nutritive condition of the animal
Note the influence of changes m diet on the food consumption The diet
consisted of mixed food for penod 1, and for periods 2 and 3 was as follows.
Constituents
Per 2
Per 3
!
$ ct
p ct
Edestm
18 0
18 0
Protein-free milk
0 0
28 2
Starch
29 5 to 32 5
23 8
Sugar
IS 0 17 0
0 0
Agar
5 0
5 0
Salt mixture I
2 5
0 0
Lard
2 $ 0 30 0
25 0
Il8 FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
Chart LXXXII
Chart LXXXI
/ Killed for
—h measurement
\l lolled
I for"
measurement
a Food eaten
U- -* -T- - -- 1 -- - ,
V
» V
^ Food eaten
r \ A
CHARTS AND THEIR EXPLANATIONS
Chart LXXXrv
Ch\rt LXXXV
Body weight
Glutenm food
Food eaten
/ v
0 20 40 60
T—killed
for measurement
1,0 - ft
//
#/
90 — f —
M
Body we ght
■ Glutemn food
Ls " V Food eaten
r v ^ i
1 -*■— killed
Ifcr measurement
Chart LXXXVI
Ki'iedfor
measurement
N-"~T
Charts LXXXIV (rat ioo, female), LXXXV *
(rat ioi, male), and LXXXVI (rat 102 , male). These §gS“ Ssto 3 4
animals, from the same family as the control rats, fljgjf a0
Charts LXXXI-LXXXIII, were maintained on a sat mixture i ^ s
diet of glutenm from wheat 124 days, when they were 31 . 0 4
killed for measurement. The chart illustrates mamtenance without appre¬
ciable growth. For other data see page 73. The diet was as shown herewith.
Olrt
120
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
Chart LXXXVII Chart LXXXVIII Chart LXXXIX
O 20 40 60
Day s
Charts LXXXVII (rat 293, female), LXXXVIII p ct
(rat 284, male), and LXXXIX (rat 279, male) show Giutemn 180
growth from an early age on a diet containing protein-free starch* free mdk 23 1
milk, m which giutemn from wheat formed the sole protein ^gar 2 | o
The an im als in growmg to several times their original
weight must have synthesized their punne- and phosphor ns-containing
complexes from punne-free food The influence of size on the food require¬
ment is shown by the food-mtake curves The diet was as shown in table
Chart XC Chart XCI
Charts XC (rat 258, female) and XCI (rat 250, p ct
male) show growth from an early age on a diet contain- ovaibamm 18 0
mg protein-free milk, in which ovalbumin formed the sole ISSS**®* “ ulk % I
protein. The animals in growing to several times their * g
original weight must have synthesized their purine-con¬
taining complexes from purine-free food. The influence of size on food re¬
quirements shown by the food-intake curves. The diet was as shown above
CHARTS AND THEIR EXPLANATIONS
121
Chart XCII
Chart XCIII.
, Lac’talbumin + Protein.
-■Tree- milk
~T / ~r
j£/
. I §
/Food eaten
0 20 4-0 60 80 u 20 Z* 0 60 80
Days 0a ys
Charts XCII (rat 251, male) and XCIII (rat
259, female) show growth from an early age on a tactaibunun 18^0 ct
diet contaimng protem-free milk, m which lactal- starch I ' fre * miIk 16 s to is s
bunun formed the sole protein The animals in s 0
growing to several times their original weight must 3u 0 33 °
have synthesized their punne- and phosphorus-containing complexes from
punne-free food The influence of size on the food requirement is shown
by the food-mtake curves. The diet was as shown herewith
Chart XCIV Chart XCV
-Gfycinin-*-Protem--free milk-r
Glycmm+Prctem-^ree mlft*
Charts XCIV (rat 257, female) and XCV (rat 241, p ct
male) show growth from an early age on a diet contain- giyamn x| o
ing protean-free milk, in which glycinin formed the sole ““ % %
protein. The animals in growing to several times their ^ "
original weight must have synthesized their purine-con- ^
taining complexes from purine-free food. The influence of size on food require¬
ment is shown by the food-intake curves. The diet was as shown herewith.
60 80
!
Glycmm
P ct.
x8 o
Protein-free milk
28 2
Starch
S 3 8
Agar
5 0
Lard
25 0
122
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES
Chart XCVT
Chart XCVI (rat 36, male) shows the failure of inhibition of growth to
check the “capacity to grow.” The rat was stunted on gliadin food for 37
days (period 1) and on casern food for 12 days (period 2) and completely
recovered growth on mixed diet during 217 days (period 3) The diet for
periods 1 and 2 was as follows:
Constituents l Per. I ^
• i
Constituents
Per 2
1
Gliadin (from wheat)
P ct.
180 1
Casein
i> ct
xS 0
Starch
29 s '
Starch
29 5
Sugar
IS 0 .
Sugar
15 0
Agar
s 0 ;
Agar
5 0
Salt mixture I
a 5
Salt mixture I
2 5
Lard
30 0 |
Lard
30 0
Chart XCVII (rat 37, male) shows unimpaired capacity for growth on
mixed diet and milk diet after an earlier period of stunted growth on gliadin
diet for 37 days (period 1) and casein diet for 12 days (period 2). Part of
the period of growth was accomplished on milk food, part on mixed food,
the change being made at 3 to mixed food, at 4 to milk food, and at 5 to
CHARTS AND THEIR EXPLANATIONS
123
mixed food again Note that this has not affected the typical character of
the curve of growth The diet was as follows
Constituents
Per 1
Constituents
Per 2 ! Perl ° ds
1 3 and 5
1
Constituents Per 4
Gliadm (from wheat)
Starch
Sugar
Agar
Salt mixture I
Lard
p ct
18 0
29 5
IS 0
5 0
2 S
30 0
Casein
Starch
Sugar 1
Agar
Salt mixture I ,
Lard '
P ct |
18 0 1 Mixed
29 5 1 food «
ISO ;
5 0 1
2 s 1 !
30 0 1
P ct
Trumilk 60 0
- Starch 16 7
' Lard 23 3
1
Chart XC\II
Days
Chart XCVIII (rat 185, male) shows the failure
of a rat to be maintained on a diet composed as
shown herewith.
Ghadin (from wheat)
p ct
18 0
Starch
29 S
Sugar
15 0
Agar
5 0
Salt mixture I
2 s
Lard
30 0
0
60
124
DEEDING EXPERIMENTS WITH ISOLATED EOOD-SUBSTANCES.
Chart XCIX
Chart C
Charts XCIX (rat 186, male) and C (rat 188, female) show the failure
of the rat to be maintained during periods i and 2 on diets mentioned below
The perfect resumption of growth when the diet consisted of milk-paste
(period 3) illustrates that the “capacity to grow” normally is not visibly
impaired by previous large loss of body-weight. The food consisted of—
Constituents
Per 1
Per 2 |
1
Constituents
Per 3
p a
p ct
i> ct
Gliadin (from wheat)
18 0
0 0 1
Trtiimlk
60 0
Ldestin
0 0
18 0 ,
Starch
is 7
Starch
29 5
32 5 ,
Salt mixture I
I 0
Sugar
IS 0
17 0 1
Lard
23 3
Agar
5 0
| 5 0 j
Salt mixture I
2 s
1 2 5
Lard
30 0
! 250 1
Chart Cl (rat 147, female) The animal, well Ghadm (fromwW) i8 £ ct
nounshed on a mixed diet during period 1, failed starch 29 5 to 34 s
to maintain its body-weight on a diet in which x | o 17 0
gliadin was the sole protein (period 2), until faeces saitmixtare 1 3 | 0 30 0
were added in penod 3. The diet consisted of
mixed food during penod 1; for periods 2 and 3 it was as shown herewith.
Chart CII (rat 142,female). The animal, well Ghadia(£romwheat ) iso *
nourished on a mixed diet during period 1, failed starch 29 s to 34 s
to maintain its body-weight on a diet in which Aga? . . X I o 17 °
gliadin was the sole protein (period 2) The addi- SaUnuxtu« 1 £ 30 0
tion of faeces to the diet in periods 3 and 4 checked
the decline During period 3 the faeces added were thoroughly sterilized and
seemed to be less efficient than the unsterilized faeces in period 4, or in other
similar experiments. The diet consisted of mixed food during period 1, for
periods 2, 3, and 4 it was as shown herewith.
CHARTS AND THEIR EXPLANATIONS
125
Ch \rt Cl
Chart CII
126
FEEDING ^XP^RIM^NTS WITH ISOIvAT^D EOOD-SUBSTANCKS.
Chaat CIII
Chart CIII (rat 130, female) The animal,
well nourished, on a mixed, diet during period 1,
failed to maintain its body-weight on a diet in
which gliadinwas the sole protein (period 2),until
faeces were added in period 3 The diet consisted
of mixed food during period 1, for periods 2 and 3
Glia.d.m (from wheat)
Starch.
Sugar
Agar
Salt mixture I
X^ard
it was as shown
p
18 o
ct
29 S to 34 S
IS o 17 o
S o
2 S
25 o 30 o
CHARTS AND THEIR EXPLANATIONS
127
Chart CIV
Chart CV
Charts CIV (rat 234, female), CV (rat 228, female), CVI (rat 235,
male), and CVII (rat 227, male) show the effect of successively larger addi¬
tions of milk -paste to gliadm food mixture which has been shown in other
experiments to be inadequate for the purposes of growth Note the more
rapid growth as the content of milk is increased The diet consisted of—
Constituents
Per 1
Per 2
Per 3
*Gliadin food
fMilk food
p ct
95
5
p ct
80
20
p ct
70
30
♦Gliadm food gliadm (from wheat) 1S0,
starch, 29 5 to *52 *{, sugar, 17 o, agar, 5 0 salt
mixture I, 2 5, lard, 25 to 28
fMilk food Trumilk, 60 o, starch, 15 7, salt
mixture I, I 0, lard, 23 3
128
FEEDING EXPERIMENTS WITH ISOLATED FOOD-SUBSTANCES.
Chart CVIII
Chart CIX
/
/
/
/
/
f/
SI
u
c
$
/
//
. /
/
/
/
6lud>rf fi
* ly-flk
aod 90%
A 10
Da/)
Y - Gha
t\ weight
)\
in free n
tlk
Food
eaten
>
i
0 20 40 60 80 100 120
Days
Chart CX
Chart CXI
Charts CVIII (rat 214, female), CIX (rat 219, male), CX (rat 220,
male), and CXI (rat 213, male) show the failure to induce more than
slight growth when gliadin forms the sole protein of the dietary, even under
conditions in which most other proteins have been found effective That
the failure to grow is not due to insuffi cient food intake is evident. The
character of the diets is given in the table below.
Period i"
Gliadin food* gtiadra {from wheat), 18 o„ starch, 32 5, sugar,
17.0; agar ,je o, salt mixture 1,2 5, lard, 25 o .
Milk food Trtmulk, 60 o; starch, IS 7; salt mixture 1 ,1 o, lard,
23-3 Pimm ■ 1
p a
90
IO
Period 2
Gliadin {from wheat) *
Protein-free milk. -, .
Starch..
Agar. .
Lard...
P Ctm
18 o
28 2
20 8
S o
28 o
0 Grams J
CHARTS AND THEIR EXPLANATIONS.
Chart CXII
Chart CXIV
Gliadm -+■ Protein-free milk ■
yr*\ Body weight
- r Gliadin-* Protein-free r-ii'kl'
/ BQOJ'-
Food eaten
■ Food eaten
Chart CXIII
Body weight
Food eaten
Charts CXII (rat 249, female),
CXIII (rat 240, female;, and CXIV
(rat 254, female) show the failure of
the animals to grow normally on a
diet containing protein-free milk and
gliadm as the sole protein It will
be noted that these animals ate well
and that the maintenance was better
than with similar gliadm mixtures
which contained no protem-free
milk The composition of the food
was as follows
Glia.din (from w heat)
Protein-free milk;
Star ell
132
FBBDING experiments with isolated food-substances.
Chart CXVIII
Chart CXIX
Charts CXVIII (rat 167, male) and CXIX (rat ct
168, male) show maintenance in period 2 on a diet Giiadm (from wheat) 18 o
containing protem-free milk and gliadin as the sole f^- freemiIk * §
protein The animals did not decline like tho se fed rfS • A 0
on gliadin without protein-free milk. Note their 0
abundant food intake. The preliminary period is introduced to show the
excellent previous nutritive condition of the rats. The composition of the
food was mixed during period 1; for period 2 it was as shown herewith.
CHARTS AND THEIR EXPLANATIONS
133
Chart CXX Chart CXXI
0 iO 40 60 80 100 120 140
Days
Charts CXX (rat 208, female) and CXXI (rat 206, female) show, mpenod
1, failure to grow on the diet indicated below, and, in period 2, nearly
normal growth on a diet containing protein-free milk m which one-quarter
of the gliadrn, previously found inadequate to induce growth, was replaced
by casein. Note the small quantity of casein which suffices to promote
growth instead of standstill This emphasizes the different nutritive
value of casein and gliadin The diets consisted of—
Constituents
Per 1
Constituents 1
Per 2
Casein or )
p ct
i
Gliadin food (gliadin (from wheat), t 8 n,
protein-free milk, 28 2, starch, 20 8,
p ct
Edestm or \
xS 0
Gliadin )
agar, 5 0, lard, 28 0 )
75
Starch
32 S
Casein food (casern, 18 0, protein-free
milk, 282, starch, 238, agar, so,
lard, 25 0)
1
Sugar
17 0
Agar
Salt mixture I
Lard
5 0
2 5
25 0
! 45
Chart CXXII
Days
Chart CXXII (rat 179, female) Period 1 shows maintenance without
growth on a diet containing salt mixture I (no protein-free mi l k ) and casein
as the sole protein. This should be contrasted with numerous similar experi¬
ments in which the inorganic constituents of the diet were present in the
134 FEEDING EXPERIMENTS with ISOLATED food-substances
form of protein-free milk Period 2 shows the influence of the substitution
by casern of one-fourth of the gliadin in a dietary repeatedly shown to suffice
for maintenance but not for growth This emphasizes the different nutri¬
tive value of casein and gliadin The composition of the diets was as shown
below.
Constituents
Per I
1 Constituents
1
Per 2
1
p ct
P ct
Casern
18 0
1 Gliadin food (gliadin (from wheat).
Starch
32 5
IS 0, protein-free milk. 28 2,
Sugar
17 0 to 20 0
starch 20 8 , agar, 5 0, lard, 28 0)
75
Agar
5 0
Casern food (casein, 18 0, protein-
Salt mixture I
2 S
free milk, 28 2, starch, 23 8 t
Lard
22 0tO23 0
agar, 5 0, lard, 25 0)
25
Chart CXXIII
Chart CXXIII (rat 173, male) Period 1 shows imperfect maintenance
without growth on a diet containing salt mixture I (no protein-free milk)
and casein as the sole protein. This should be contrasted with numerous
similar experiments in which the inorganic constituents of the diet were
present in the form of protein-free milk. Period 2 shows the influence of the
substitution by casein of one-fourth of the gliadin m a dietary repeatedly
shown to suffice for maintenance but not for growth This emphasizes the
different nutritive value of casein and gliadm The composition of the
diets was—
Constituents Per 1
Constituents
Per 2
„ - P ct
Casein ' 18 0 ,,
Starch 32 5
Sugar 17 0 to 20 0 |
Agar 5 0 1
Salt mixture I 2 5 1
Lard 22 0 25 0 |
'1
Gliadin food (gliadin (from wheat),
18 o, protein-free milk, 28 2,
starch, 20 8 , agar, 5 0, lard, 28 0 )
Casein food (casein, 18 0, protem-
freemilk, 28 2, starch,23 8, agar,
5 0, lard, 25 0)
p ct
75
25
CHARTS AND TH^IR ^XFIvAISTATlONS
Chart CXXIV
Chart CXXV
Charts CXXIV (rat 256, female) and. CXXV (rat 255, female) show
maintenance without growth of medium-sized rats on a diet of protein-free
milk: and hordein, from barley, as the sole protein Note the undimmished
appetite during course of experiment Precisely similar mixtures contain¬
ing other single proteins have sufficed to induce growth This experiment
demonstrates the different nutritive value of hordein and most other pro¬
teins and its resemblance in this respect to the chemically similar protein
gliadin. This is a marked instance of the relation of the chemical consti¬
tution of the protein to nutrition The composition of the food was as
shown herewith
Hordein
Protein-free milk
Starch
Agar
Lard
p ct
18 o
28 2
16 8 to 18 8
5 o
30 O 32 O
penods
,
Constituents
I and 3
1 Constituents
Per 2
Per 4
i> ct
1
P ct
p ct
Dog biscuit
5 S 33
, Zem
16 89
IO 77
Lard
41 66
J Starch
IO 14
23 70
1 j Sugar
8 78
21 54
Salt mixtm e
3 38
2 15
1 1 Agar
IO 14
5 17
) | Lard
50 67
36 63
260
Chart CXXVIII (rat 146, male) shows the failure Period 2
of a well-nourished rat (see period 1) to be maintained z e m is
on a diet containing protein-free milk and zem as the sole f£^*£ 1 " free
protein It should be noted that precisely similar mix- Agag
tures m which zem was replaced by any of the other pro- “
terns stu di ed, sufficed either to induce growth or at least to maintain body-
weight for an equally long period Attention is directed to the continued
fall m weight despite the large food intake- 'The composition of the food
was mixed for period 1, for period 2 it was as shown herewith.
0 (100 0 0
^^DING ^XP^RIM^NTS WITH ISOLATED EOOD-SUBSTANCES
133
Ch«t CXXIX
Chart CXXIX (rat 157, male) shows the failure of
a well nourished, rat (see period 1), to he maintained on a
diet containing protein-free milk and zem as the sole
protein- It should be noted that precisely s imi lar mix¬
tures in which zein was replaced by any of the other
proteins studied, sufficed either to induce growth or at least to maintain
body-weight for an equally long period Attention is directed to the con¬
tinued fall m weight despite the large food intake The composition of the
food was mixed for period 1; for period 2 it was as shown herewith.
Period ss p ct
Zem 18
Protein-free milk 28
Starcb. 23
Agar 5
lard 25
New Haven, Connecticut, U. S. A.,
July i, 1911.
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